fix: address Copilot review (9 comments)

#1 GitView: hide/disable 'open in editor' for external linked worktrees
   (path outside session workspace is rejected by the fence); add
   isWithinWorkspace client helper for the gate.
#2 DiffTab: untracked diff read resolves against diff.repoRoot (child-repo
   paths are repo-root-relative, not cwd-relative); fs.read route threads
   selectedRepoOf into resolveGitPath so the host resolves the right base.
#3 GitView: chooseRepo handler mirrors chooseWorktree — clears status/
   history/log and bumps generation before async refresh, preventing stale
   rows from acting on the newly selected repository.
#4 git.ts: repoRoots/repoRoot compare roots via pathIdentity() (platform-
   aware) instead of raw includes(), fixing win32 forward/backslash
   mismatch that silently fell back to roots[0].
#5 markdown-images: mask fenced code blocks and inline code spans before
   rewriting; only rewrite reference definitions whose label is actually
   referenced by image syntax (not plain links). +3 tests.
#6 package.json: downgrade unrun ^0.3.1 → ^0.2.39 (0.3.x requires Node
   ^22.13, incompatible with declared engines >=20).
#7 market-manifest.spec: shell:true on win32 so execFileSync resolves the
   pnpm .cmd shim.
#8 smoke.spec: build html-route URL via encodeHtmlUrl() (production
   encoder) so the Windows drive separator is correct.
#9 index.ts git.worktrees route: thread selectedRepoOf so a workspace
   container's selected child repo's linked worktrees appear.

src/git.ts

@@ -212,7 +212,7 @@ export async function repoRoots(cwd: string): Promise<string[]> {
       .sort((left, right) => left.name.localeCompare(right.name))) {
       try {
         const root = await directRepoRoot(join(cwd, entry.name))
-        if (!roots.includes(root)) roots.push(root)
+        if (!roots.some(existing => pathIdentity(existing) === pathIdentity(root))) roots.push(root)
       } catch {
         // Ordinary child directory; keep discovering sibling repositories.
       }
@@ -225,7 +225,13 @@ export async function repoRoots(cwd: string): Promise<string[]> {
 export async function repoRoot(cwd: string, selected?: string): Promise<string> {
   const roots = await repoRoots(cwd)
   if (roots.length === 0) throw new GitCommandError('not a git repository', 'not-repo', 'rev-parse')
-  if (selected !== undefined && roots.includes(selected)) return selected
+  // Git for Windows may return forward-slash roots while callers pass
+  // backslashes (or vice-versa); compare via the platform-aware identity.
+  if (selected !== undefined) {
+    const identity = pathIdentity(selected)
+    const match = roots.find(root => pathIdentity(root) === identity)
+    if (match !== undefined) return match
+  }
   return roots[0]!
 }