When a claude-mem DB is synced between machines running different versions,
orphaned indexes can reference non-existent columns (e.g. idx_observations_content_hash
referencing content_hash). This causes SQLite to throw "malformed database schema"
on ALL queries, including PRAGMAs, creating a silent 503 failure loop.
The fix detects this on startup, uses Python's sqlite3 module to drop the
orphaned schema objects (bun:sqlite doesn't support writable_schema modifications),
resets migration versions, and lets the idempotent migration system recreate
everything properly.
Fixes#1307
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>