Reliably restore last session on refresh after a server restart

The page-load restore was one-shot and bailed when a completed scan's
replayed scan_phase left a running flag set; sse_replay_done (the other
retry) only fires for a non-empty replay buffer, which is empty after a
restart — so refreshing post-update showed a blank grid despite the
results being in the DB. The watchdog now retries the restore on each
4s poll while nothing is shown and no scan runs, clearing stale flags
first. /api/scan/status also reports google_running separately so a
refresh during a live Google scan is no longer treated as idle.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

routes/scan.py

@@ -76,9 +76,13 @@ def scan_status():
     acquired = state._scan_lock.acquire(blocking=False)
     if acquired:
         state._scan_lock.release()
+    g_acquired = state._google_scan_lock.acquire(blocking=False)
+    if g_acquired:
+        state._google_scan_lock.release()
     return jsonify({
-        "running":  not acquired,
-        "scan_id":  _sse_mod._current_scan_id or None,
+        "running":         not acquired,     # M365 + file scan lock
+        "google_running":  not g_acquired,   # Google scan lock (separate)
+        "scan_id":         _sse_mod._current_scan_id or None,
     })