fix: root cause — sqlite_patch not applied when DATABASE_URL empty

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

salesflow-saas/backend/Dockerfile

@@ -19,7 +19,7 @@ RUN pip install --no-cache-dir --upgrade pip setuptools wheel \
 FROM python:3.12-slim AS runtime
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    libpq5 curl tini \
+    libpq5 curl tini libxml2 libxslt1.1 \
     && rm -rf /var/lib/apt/lists/*
 
 RUN groupadd --gid 1000 app \
@@ -38,7 +38,7 @@ USER app
 
 EXPOSE 8000
 
-HEALTHCHECK --interval=30s --timeout=10s --start-period=90s --retries=5 \
+HEALTHCHECK --interval=20s --timeout=15s --start-period=120s --retries=5 \
     CMD curl -f http://localhost:${PORT:-8000}/health || exit 1
 
 ENTRYPOINT ["tini", "--"]

salesflow-saas/backend/app/sqlite_patch.py

@@ -139,7 +139,7 @@ def apply_patch():
     import sys
     import types
     db_url = _get_db_url()
-    if "sqlite" in db_url.lower():
+    if not db_url or "sqlite" in db_url.lower():
         # Patch PostgreSQL dialect
         sys.modules["sqlalchemy.dialects.postgresql"] = _FakePGModule()  # type: ignore
 

salesflow-saas/backend/start.sh

@@ -1,6 +1,7 @@
 #!/bin/sh
 set -e
 echo "[dealix] PORT=$PORT"
+echo "[dealix] DATABASE_URL prefix: $(echo ${DATABASE_URL:-NOT_SET} | cut -d: -f1)"
 echo "[dealix] Testing imports..."
 python3 -c "
 try: