Adds the "Who's using Ask?" picker (GET /api/ask/users), actor
resolution via x-ask-user (src/lib/agent/context.ts), and thread
persistence (src/lib/chat/threads.ts, /api/chat/threads routes).
/api/chat now accepts { threadId?, message, display?, images? } and
persists each turn as its own append-only ask_messages row; the old
{ history } body still works for one release. chat-view.tsx gained the
picker, a thread sidebar (new/select/rename/archive), and ?thread=<id>
in the URL.
Live browser check skipped: ask_threads/ask_messages/ask_log don't
exist yet in the target PocketBase (Task 1's schema is dry-run only,
pending the user's --apply). Covered by mocked unit tests instead.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
