fix: retarget orphan changeset from manifest-model-router to manifest

[brunobuddy]

Problem

Release workflow failing on the merge of #1545:

```
🦋 error Found changeset remove-local-mode for package manifest-model-router which is not in the workspace
```

`.changeset/remove-local-mode.md` was added in #1539 (`chore/remove-local-mode`) but targets `"manifest-model-router": patch`. That package was deleted in #1528, so changesets fast-fails on the dangling reference. Same class of problem as #1534.

Fix

Unlike #1534 where I deleted the orphans outright, this one has genuinely useful changelog content — it documents the local-mode removal, the Docker hardening, the new `AUTO_MIGRATE` env var, and the unified `EMAIL_*` scheme. Those are real user-facing changes and they belong in the `manifest` CHANGELOG.

So: retarget the changeset from `manifest-model-router` to `manifest` (the canonical version from #1541). Keep the `patch` bump type — if you want `minor` or `major` instead, that's a one-line follow-up, but I don't want to make that call for you.

Also dropped the final sentence of the body, which described `manifest-model-router` as "the recommended way to route OpenClaw requests through Manifest" — that package no longer exists. Replaced with a correct note pointing users at the dashboard's setup modal (generic OpenAI-compatible provider config).

Verified locally

```
$ npx changeset status --verbose
🦋 info Packages to be bumped at patch
🦋 - manifest 5.46.1
🦋 - .changeset/remove-local-mode.md
```

Clean resolve. Release workflow should succeed on the merge.

Test plan

• `npx changeset status` — resolves cleanly, bumps manifest from 5.46.0 to 5.46.1
• After merge: release workflow opens a `chore: version packages` PR with the `manifest@5.46.1` bump + a new entry in `packages/manifest/CHANGELOG.md`

Follow-up thought

After this lands and the version-packages PR is merged, it might be worth a quick audit to make sure no other PRs in flight have orphan changesets. The pattern is always the same: a PR branched off main before #1528 landed adds a changeset targeting a now-deleted package. A one-liner `grep -rl '"manifest-model-router"' .changeset/` on any release-blocking branch would catch this early.

---

Summary by cubic

Retargeted .changeset/remove-local-mode.md from manifest-model-router to manifest to unblock the release workflow and put the changelog in the right package. Updated the final note to remove the deleted plugin and direct OpenClaw users to configure Manifest as a generic OpenAI-compatible provider.

^{Written for commit 5344510. Summary will update on new commits.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.93%. Comparing base (1cdf0a9) to head (5344510).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1546   +/-   ##
=======================================
  Coverage   97.93%   97.93%           
=======================================
  Files         118      118           
  Lines        8581     8581           
  Branches     3230     3230           
=======================================
  Hits         8404     8404           
  Misses        175      175           
  Partials        2        2           

Flag	Coverage Δ
frontend	97.93% <ø> (ø)
shared	100.00% <ø> (ø)

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