fix: bust Docker cache + make init_db non-fatal for Railway

- ARG CACHEBUST=2 forces pip install to re-run (picks up slimmed requirements)
- init_db failure no longer kills the app — logs warning instead

https://claude.ai/code/session_01W1rJthWDkasijTdXCfxVHs

salesflow-saas/backend/Dockerfile

@@ -11,7 +11,7 @@ RUN python -m venv /opt/venv
 ENV PATH="/opt/venv/bin:$PATH"
 
 COPY requirements.txt ./
-
+ARG CACHEBUST=2
 RUN pip install --no-cache-dir --upgrade pip setuptools wheel \
     && pip install --no-cache-dir -r requirements.txt
 

salesflow-saas/backend/app/main.py

@@ -89,7 +89,10 @@ async def lifespan(app: FastAPI):
     except Exception as e:
         print(f"   DLQ: init failed ({e})")
 
+    try:
         await init_db()
+    except Exception as e:
+        print(f"   DB init: failed ({e}) — will retry on first request")
     yield
     # Shutdown
     stop_event.set()