Remove legacy macOS E2E suite (CrabNebula)

- Playwright E2E fully covers all 15 macOS E2E tests; no unique coverage lost
- Delete `test/e2e-macos/`, `test/e2e-shared/helpers.ts`, `.env.example`
- Remove `automation` Cargo feature, `tauri-plugin-automation` dep, and plugin init in `lib.rs`
- Remove 9 npm devDeps: `@crabnebula/*`, `@wdio/*`, `webdriverio`
- Remove scripts, eslint ignore, and doc references in `AGENTS.md`, `architecture.md`, `test/CLAUDE.md`
- Fix smb2 API breakage: add `dfs_enabled`/`dfs_target_overrides` to all `ClientConfig` sites, change `with_smb` to pass `&mut Tree`

Author: vdavid

AGENTS.md

@@ -100,7 +100,6 @@ Always use the checker script for compilation, linting, formatting, and tests. I
   - Svelte: `cd apps/desktop && pnpm vitest run -t "<test_name>"`
 - E2E (Playwright): See `apps/desktop/test/e2e-playwright/CLAUDE.md` — build with `playwright-e2e` feature, start app,
   run tests
-- E2E (legacy): See `apps/desktop/test/e2e-linux/CLAUDE.md` and `apps/desktop/test/e2e-macos/CLAUDE.md`
 - Ubuntu test VM: See `apps/desktop/test/e2e-linux/CLAUDE.md` § "Ubuntu test VM"
 - CI: Runs on PRs and pushes to main for changed files. Full run: Actions → CI → "Run workflow".