chore: update v3 release with main (#7507)

# Pull Request

## 📖 Description

Brings `releases/fast-element-v3` up to date with `main`. Cherry-picks every commit landed on `main` after PR #7477 was merged (the last v3↔main sync) and adds an adaptation commit so the changes work with the v3 architecture (where `@microsoft/fast-html` was merged into `@microsoft/fast-element` under `src/declarative/`).

Cherry-picked (in chronological order):

- #7479 — feat: change default attribute-name-strategy from none to camelCase
- #7494 — chore(deps): bump liquidjs 10.25.6 → 10.25.7
- #7501 — chore: migrate TypeScript compilation to `typescript/native-preview` (`tsgo`)
- #7502 — feat: allow `fast-build` rendering without state
- #7503 — docs: per-package documentation reorg (DESIGN.md/README.md and `docs/architecture/*`)
- #7504 — feat: propagate shadowroot attributes
- #7505 — chore: bump packages after failed publish (`fast-build` → 0.5.0)
- #7469 — feat: add build utilities and SSR renderer to `@microsoft/fast-test-harness`
- #7506 — chore: prepare `@microsoft/fast-test-harness` package for publishing

The "applying package updates" beachball commit (`aad6f5481`) was intentionally skipped — v3 maintains its own versioning track (`fast-element@3.0.0-rc.1`, `fast-test-harness@0.0.1`) and runs its own publish.

Adaptation commit highlights:

- Adds a new `./declarative-syntax.js` subpath export to `@microsoft/fast-element` so tooling consumers (e.g. `fast-test-harness` build utilities) can access declarative HTML syntax constants from fast-element directly. Mirrors the existing `./declarative-utilities.js` subpath.
- Re-points `fast-test-harness/src/build/generate-templates.ts` and `generate-webui-templates.ts` from `@microsoft/fast-html/syntax.js` to the new subpath.
- Replaces the removed `RenderableFASTElement(...).defineAsync({ templateOptions })` pattern with v3's `Element.define()` in test fixtures and the README example.
- Drops `@microsoft/fast-html` from the harness Vite optimizer exclude list.
- Excludes `*.spec.ts` from the fast-element TS build (the declarative `.spec.ts` files import `@playwright/test`, whose `.d.ts` files are incompatible with `tsgo`'s stricter parser; these specs are still type-checked when run via the declarative Playwright config).
- Adapted hydration marker handling in `crates/microsoft-fast-build/src/node.rs` for #7502 (kept v3's `inject_count_marker` / `data-fe="N"` style while merging in main's `Option<&mut HydrationScope>` flow).
- All `packages/fast-html/*` paths from cherry-picks were dropped (the package no longer exists on v3); related `change/@microsoft-fast-html-*.json` files were either converted to `@microsoft-fast-element-*.json` or dropped where they no longer apply.

## 📑 Test Plan

Run from the monorepo root on this branch:

- `npm run build` — all 6 packages build successfully (fast-build, fast-element, fast-router, fast-test-harness, fast-site, fast-todo-app-example).
- `@microsoft/fast-element` — 1410 chromium playwright tests + 176 declarative chromium tests pass.
- `@microsoft/fast-test-harness` — 96 node unit tests + 43 chromium playwright tests pass.
- `npm run biome:check` — clean.
- `npm run checkchange` — passes.

## ✅ Checklist

### General

- [x] I have included a change request file using `$ npm run change`
- [ ] I have added tests for my changes.
- [x] I have tested my changes.
- [x] I have updated the project documentation to reflect my changes.
- [x] I have read the [CONTRIBUTING](https://github.com/microsoft/fast/blob/main/CONTRIBUTING.md) documentation and followed the [standards](https://github.com/microsoft/fast/blob/main/CODE_OF_CONDUCT.md#our-standards) for this project.

Author: janechu

.github/copilot-instructions.md

@@ -41,11 +41,13 @@ Each package includes a DESIGN.md file, read that to gain a general understandin
 These contain domain-specific guidance. Read when performing related tasks:
 
 - [TypeScript](./skills/typescript/SKILL.md) — compiler constraints, import/export conventions, decorator usage, testing patterns.
+- [Rust](./skills/rust/SKILL.md) — general guidance on performing updates between the crate and package.
 - [Shipping](./skills/shipping/SKILL.md) — pull request format, change file generation, documentation updates.
 - [Pull Request](./skills/fast-pull-request/SKILL.md) — generate a pull request description from the branch diff.
 - [Bug Report](./skills/fast-bug-report/SKILL.md) — generate a bug report issue from conversation context.
 - [Feature Request](./skills/fast-feature-request/SKILL.md) — generate a feature request issue from conversation context.
 - [Testing](./skills/testing/SKILL.md) — running tests locally and in CI, writing Playwright fixture tests.
+- [Documentation](./skills/documentation/SKILL.md) — adding documentation in code, markdown files in each package/crate, and the website.
 
 ## Commands
 

.github/skills/documentation/SKILL.md

@@ -0,0 +1,18 @@
+---
+name: documentation
+description: Add documentation for contributors and developers.
+---
+
+Documentation exists in 3 forms, code comments, design/architectural documentation that is made up of markdown files describing code flow and core concepts (such as DESIGN.md), and the documentation website.
+
+Design/architectural documentation such as DESIGN.md should always be kept up-to-date.
+
+The website captures the documentation primarily for the `@microsoft/fast-element` package. Other packages are treated as tangential, so testing packages or other utilities should have their own sections.
+
+The website has been written in 11ty and primarily consists of markdown files. When making changes, ensure that the website has been scanned on whichever latest major version is available. These are organized by folder, so if 1.x/2.x/3.x folders are available, you will update the documentation in the 3.x folder.
+
+If you are making a breaking change, ensure the migration document has been updated.
+
+All markdown documentation aside from the package/crate level DESIGN.md files are in that package/crates docs folder.
+
+Any documentation created for the website should be written with the developer implementing the package in mind, it is not intended for other audiences.

.github/skills/rust/SKILL.md

@@ -0,0 +1,12 @@
+---
+description: Use this guide when working on Rust changes in the FAST monorepo.
+name: rust
+---
+
+# Working with the Rust crate and the Rust NodeJS CLI
+
+The primary location for the Rust logic should exist within a crate. If the logic is made accessible in the NodeJS environment via wrapping the crate and using a wasm bindgen, as much as possible any logic that exists in Rust should not be duplicated in JavaScript/TypeScript.
+
+## Breaking changes
+
+Understand [semver](https://semver.org/) and check the crate and package version. If the version is currently in a prerelease state, update the APIs with breaking changes as necessary and ensure that any generated pull request descriptions capture this.

.github/workflows/ci-validate-platforms.yml

@@ -74,11 +74,11 @@ jobs:
         run: cargo install wasm-pack
 
       - name: Build workspaces
-        run: npx lage build ${{ github.event_name == 'pull_request' && '--since origin/main' || '' }} --allow-no-target-runs
+        run: npx lage build ${{ github.event_name == 'pull_request' && '--since origin/main' || '' }} --allow-no-target-runs --verbose
 
       - name: Install playwright dependencies and browsers
         run: |
           npx playwright install --with-deps
 
       - name: Run tests in all Packages
-        run: npx lage test:node test:playwright ${{ github.event_name == 'pull_request' && '--since origin/main' || '' }} --allow-no-target-runs
+        run: npx lage test:node test:playwright ${{ github.event_name == 'pull_request' && '--since origin/main' || '' }} --allow-no-target-runs --verbose

.github/workflows/ci-validate-pr.yml

@@ -58,14 +58,14 @@ jobs:
       run: cargo install wasm-pack
 
     - name: Build workspaces
-      run: npx lage build ${{ github.event_name == 'pull_request' && format('--since origin/{0}', github.event.pull_request.base.ref) || '' }} --allow-no-target-runs
+      run: npx lage build ${{ github.event_name == 'pull_request' && format('--since origin/{0}', github.event.pull_request.base.ref) || '' }} --allow-no-target-runs --verbose
 
     - name: Install playwright dependencies and browsers
       run: |
         npx playwright install --with-deps
 
     - name: Testing unit tests
-      run: npx lage test:node test:chromium ${{ github.event_name == 'pull_request' && format('--since origin/{0}', github.event.pull_request.base.ref) || '' }} --allow-no-target-runs
+      run: npx lage test:node test:chromium ${{ github.event_name == 'pull_request' && format('--since origin/{0}', github.event.pull_request.base.ref) || '' }} --allow-no-target-runs --verbose
 
     - name: Testing final validation
       run: npm run test:validation

.github/workflows/ci-webui-integration.yml

@@ -41,7 +41,7 @@ jobs:
       run: cargo install wasm-pack
 
     - name: Build workspaces
-      run: npm run build
+      run: npm run build -- --verbose
 
     - name: Install Playwright browsers
       run: npx playwright install --with-deps chromium

change/@microsoft-fast-build-182ff259-711c-45c5-8be6-8925f2d78e79.json

@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "feat: propagate shadowroot attributes",
+  "packageName": "@microsoft/fast-build",
+  "email": "7559015+janechu@users.noreply.github.com",
+  "dependentChangeType": "none"
+}

change/@microsoft-fast-build-5aac0659-95f9-4cb6-997d-252316b7841c.json

@@ -0,0 +1,7 @@
+{
+  "type": "none",
+  "comment": "chore: bump packages after failed publish",
+  "packageName": "@microsoft/fast-build",
+  "email": "7559015+janechu@users.noreply.github.com",
+  "dependentChangeType": "none"
+}

change/@microsoft-fast-build-9d7b843d-87a6-4f82-9db2-039234d8ad6e.json

@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "feat: allow fast-build rendering without state; omitted CLI state no longer probes state.json",
+  "packageName": "@microsoft/fast-build",
+  "email": "7559015+janechu@users.noreply.github.com",
+  "dependentChangeType": "none"
+}

change/@microsoft-fast-element-0e87a967-3dbb-4010-9c3f-c5dad8ef3532.json

@@ -1,6 +1,6 @@
 {
-  "type": "major",
-  "comment": "remove FASTGlobal version tracking",
+  "type": "prerelease",
+  "comment": "BREAKING CHANGE: remove FASTGlobal version tracking",
   "packageName": "@microsoft/fast-element",
   "email": "7559015+janechu@users.noreply.github.com",
   "dependentChangeType": "none"