Add graceful error handling for db-sync initialization

main.py

@@ -29,6 +29,7 @@ from fastapi import FastAPI, Request, HTTPException, Query, Header, Depends
 from fastapi.responses import JSONResponse
 from pydantic import BaseModel
 import asyncpg
+from asyncpg.exceptions import UndefinedTableError, PostgresError
 import redis.asyncio as redis
 
 # Configure logging
@@ -109,6 +110,28 @@ app = FastAPI(
 )
 
 
+# ============ Exception Handlers ============
+
+@app.exception_handler(UndefinedTableError)
+async def handle_undefined_table(request: Request, exc: UndefinedTableError):
+    """Handle missing tables (db-sync still initializing)."""
+    logger.warning(f"Database not ready: {exc}")
+    return JSONResponse(
+        status_code=503,
+        content={"error": "db_sync_not_ready", "message": "Database sync in progress. Tables not yet created."}
+    )
+
+
+@app.exception_handler(PostgresError)
+async def handle_postgres_error(request: Request, exc: PostgresError):
+    """Handle general postgres errors."""
+    logger.error(f"Database error: {exc}")
+    return JSONResponse(
+        status_code=503,
+        content={"error": "database_error", "message": str(exc)}
+    )
+
+
 # ============ Models ============
 
 class APIKeyCreate(BaseModel):