fix(workspace-state): stop resync loop on non-git folders and allow retry for degraded watcher

Gate git refresh on .git presence so file churn in non-git workspaces no longer produces endless resync_hint events, and silently log tree/git refresh errors during watch flushing instead of flagging requires_resync, which turned transient failures into self-reinforcing loops.

Degrade gracefully when the filesystem watcher fails to attach (e.g. permission denied, inotify quota): keep the initial snapshot, surface a degraded flag, and expose a store-level restart that the banner uses to retry attachment after the root cause is fixed.

Propagate is_git_repo through the snapshot so the git log and changes tabs render a dedicated "Not a Git repository" empty state instead of raw git stderr with a useless retry button.

Stop polling get_git_branch from the title bar once it returns null and re-arm on visibility change.

Add translations for the new banner, empty-state, and retry keys across all ten locales.

src/lib/app-error.ts

@@ -46,6 +46,14 @@ export function extractAppCommandError(error: unknown): AppCommandError | null {
   }
 }
 
+export function isNotAGitRepoError(error: unknown): boolean {
+  const appError = extractAppCommandError(error)
+  const candidates = [appError?.detail, appError?.message]
+  return candidates.some(
+    (text) => typeof text === "string" && /not a git repository/i.test(text)
+  )
+}
+
 export function toErrorMessage(error: unknown): string {
   const appError = extractAppCommandError(error)
   if (appError) {

src/lib/types.ts

@@ -897,6 +897,8 @@ export interface WorkspaceSnapshotResponse {
   tree_snapshot: FileTreeNode[] | null
   git_snapshot: WorkspaceGitEntry[] | null
   deltas: WorkspaceDeltaEnvelope[]
+  degraded: boolean
+  is_git_repo: boolean
 }
 
 export interface GitLogResult {