fix(watcher): cap startup wait

AGENTS.md

@@ -63,6 +63,8 @@ Non-obvious bits:
 - **Ignore layering.** Always-ignore baseline (`.git/`, `.DS_Store`) +
   root `.gitignore` parsed via the `ignore` package + a small fallback
   for non-git workspaces. Nested gitignores aren't supported yet.
+- **Startup readiness.** The daemon waits for chokidar's initial scan, capped
+  at 5s, so first requests don't hang indefinitely on huge workspaces.
 - **Debounce.** 50ms quiet period, capped at 500ms max wait so sustained
   event streams (branch switches) still flush in bounded time.
 - **Watcher and mtime-sync coexist.** When the agent edits a file we'll