Root cause: sqlite_patch checked `if "sqlite" in db_url` but db_url
was empty string when DATABASE_URL env var not set. Patch was skipped,
then models used PostgreSQL types (JSONB/Vector) with SQLite compiler
causing crash: "can't render element of type JSONB".
Fix: `if not db_url or "sqlite" in db_url` — apply patch when URL
is empty (defaults to SQLite anyway in database.py).
Also:
- Dockerfile: add libxml2/libxslt1.1 for lxml runtime
- Dockerfile: increase healthcheck start-period to 120s
- start.sh: log DATABASE_URL prefix for debugging
https://claude.ai/code/session_01W1rJthWDkasijTdXCfxVHs
