fix: set local DB ready immediately when re-syncing with existing data
f2c6d29 intended to keep local FTS serving during re-sync by only
calling setReady(false) on first-ever sync. But is_ready initializes
to false, so the has_data branch needed an explicit setReady(true).
Without it, every deploy caused ~60min of turso fallback (3-5s per
search) until fullSync completed.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>