fix(app): normalize watcher paths

[pascalandr]

Issue for this PR

Closes #17780

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Watcher events on Windows can arrive with backslash-separated paths while open tabs and cached file tree entries are keyed with forward slashes. This normalizes watcher-side paths before matching open files or loaded file tree nodes. It also refreshes the nearest loaded ancestor for add/unlink events so changes under unloaded child directories still update the visible tree.

This intentionally keeps the fix scoped to the watcher invalidation path rather than changing general path normalization behavior.

How did you verify your code works?

• bun test --preload ./happydom.ts ./src/context/file/watcher.test.ts from packages/app
• bun test --preload ./happydom.ts ./src/context/file/path.test.ts ./src/context/file/watcher.test.ts from packages/app
• bun typecheck from packages/app
• pre-push bun turbo typecheck

Screenshots / recordings

N/A, non-UI change.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

The search found one potentially related PR:

fix(watcher): filter ignored paths before publishing events, handle worktree git dirs - This PR also addresses watcher path handling, though it focuses on filtering ignored paths and handling git worktree directories rather than normalizing Windows path separators. It could be related depending on whether there's overlap in the watcher path processing logic.

However, this appears to be a different issue (PR #21453 is about filtering ignored paths, while PR #24341 is about normalizing path separators on Windows).

No other duplicate PRs found addressing the same issue #17780 or the same path normalization problem.

[pascalandr]

#21453 is related to watcher processing, but it addresses a different layer:

• fix(watcher): filter ignored paths before publishing events, handle worktree git dirs #21453 filters ignored/backend watcher events before publication and avoids VCS refreshes for git-dir events.
• This PR handles the app file-context invalidation path for Bug: file watcher paths stop matching open files on Windows #17780, where already-published watcher paths can use Windows backslashes while open tabs/file tree keys use forward slashes. It also refreshes the nearest loaded ancestor for add/unlink events.

So the two changes should be complementary rather than duplicates.