Fix seeder crash on null game data and disable SQL logging by default

Skip games with null route data (Gen 8-9 have no PokeAPI encounters)
and silence SQLAlchemy echo unless --verbose/-v is passed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/app/seeds/__main__.py

@@ -8,10 +8,13 @@ Usage:
 import asyncio
 import sys
 
+from app.core.database import engine
 from app.seeds.run import seed, verify
 
 
 async def main():
+    verbose = "--verbose" in sys.argv or "-v" in sys.argv
+    engine.echo = verbose
     await seed()
     if "--verify" in sys.argv:
         await verify()