Fix alembic path in entrypoints for both Docker and dev

In Docker images, alembic.ini is at /app/alembic.ini (no service subdir).
In dev, it's at /app/{service}/alembic.ini (bind-mounted). Now tries the
service dir first, falls back to current dir.

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

federation/entrypoint.sh

@@ -36,7 +36,7 @@ conn.close()
 " || echo "DB creation failed (non-fatal), continuing..."
 
   echo "Running federation Alembic migrations..."
-  (cd federation && alembic upgrade head)
+  if [ -d federation ]; then (cd federation && alembic upgrade head); else alembic upgrade head; fi
 fi
 
 # Clear Redis page cache on deploy