Tier 0 scalability: PgBouncer, Redis split, DB split, workers

T0.1: Separate redis-auth service (64mb, noeviction) for auth state
T0.2: Bump data Redis from 256mb to 1gb
T0.3: Per-app DATABASE_URL via PgBouncer to per-domain databases
T0.4: PgBouncer service (transaction mode, pool=20, max_conn=300);
      session.py pools reduced to 3+5 with timeout and recycle
T0.5: Hypercorn --workers 2 --keep-alive 75 on all 6 entrypoints

Deploy requires running split-databases.sh first to create per-domain
databases from the existing appdb.

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

federation/entrypoint.sh

@@ -29,4 +29,4 @@ fi
 
 # Start the app
 echo "Starting Hypercorn (${APP_MODULE:-app:app})..."
-PYTHONUNBUFFERED=1 exec hypercorn "${APP_MODULE:-app:app}" --bind 0.0.0.0:${PORT:-8000}
+PYTHONUNBUFFERED=1 exec hypercorn "${APP_MODULE:-app:app}" --bind 0.0.0.0:${PORT:-8000} --workers ${WORKERS:-2} --keep-alive 75