fix(checkpoints): canonicalize core.worktree comparison to prevent Windows path mismatch failures

[0xMink]

Closes #11343

Summary

• initShadowGit() compared core.worktree to this.workspaceDir using raw string equality, which fails on Windows when git stores the path with forward slashes but VS Code resolves it with backslashes, or when drive-letter casing differs
• Reused the existing arePathsEqual() utility from src/utils/path.ts which already handles path normalization and case-insensitive comparison on Windows
• Added .trim() on core.worktree output to handle trailing whitespace/newlines from git config reads
• Added explicit fail-closed guard: missing core.worktree now throws a clear error instead of producing a misleading mismatch message

Test plan

• New: trailing-newline in core.worktree does not cause false mismatch (stub-based integration test)
• New: missing core.worktree throws explicit error (integration test with config unset)
• Existing: all 31 prior tests continue to pass
• Total: 33 tests passing

[roomote]

Rooviewer   See task

Both issues from the previous review are resolved. No new issues found.

• normalizePathForCompare duplicates existing arePathsEqual() -- consider reusing it with .trim() on the git output instead of introducing a new function
• Test "treats forward and backslash paths as equal on Windows" fails on Linux CI because path.resolve/path.normalize don't convert backslashes to forward slashes on POSIX

Previous reviews

• c30f78a: Review #1

_{Mention @roomote in a comment to request specific changes to this pull request or fix all unresolved issues.}

[roomote]

The codebase already has arePathsEqual() which handles path normalization, trailing separator stripping, and case-insensitive comparison on win32. Using it here would avoid the duplication and the cross-platform test issues described in the next comment. The only gap is .trim() for git config output, which can be applied to the worktree value before passing it to arePathsEqual:

Suggested change

	/**
	* Normalizes a file path for comparison by resolving relative segments,
	* canonicalizing separators, and stripping trailing separators.
	* On Windows, also lowercases for case-insensitive comparison.
	*/
	export function normalizePathForCompare(p: string, isWindows = process.platform === "win32"): string {
	let normalized = path.resolve(path.normalize(p.trim()))
	const root = path.parse(normalized).root
	if (normalized.length > root.length && normalized.endsWith(path.sep)) {
	normalized = normalized.slice(0, -1)
	}
	if (isWindows) {
	normalized = normalized.toLowerCase()
	}
	return normalized
	}
	import { arePathsEqual } from "../../utils/path"

Then at the comparison site: if (!arePathsEqual(worktree?.trim(), this.workspaceDir)). This was also the approach suggested by the issue investigator in #11343 (comment).

_{Fix it with Roo Code or mention @roomote and request a fix.}

[roomote]

This test fails on non-Windows CI (confirmed locally: 1 failed | 6 passed). Node.js path.resolve/path.normalize use the host OS's separator conventions, so on Linux backslashes are treated as literal filename characters, not separators. The isWindows parameter only controls case-folding, not separator behavior. The result on Linux is:

Expected: ".../c:/users/dennis/repo"
Received: ".../c:\users\dennis\repo"

If normalizePathForCompare is kept, this test needs to either be skipped on non-Windows platforms (describe.skipIf(process.platform !== "win32")) or restructured to not depend on cross-platform path module behavior.

_{Fix it with Roo Code or mention @roomote and request a fix.}

[0xMink]

Thanks, good catches. Updated the PR:

• Removed normalizePathForCompare() and switched to the existing arePathsEqual() from src/utils/path.ts
• Added .trim() on core.worktree output before comparison to handle trailing whitespace from git
• Replaced the unit tests with two platform-stable integration tests: one verifying trailing-newline tolerance via a stub on getShadowGitConfigWorktree, and one verifying the explicit throw when core.worktree is missing
• 33/33 tests passing on Windows