perf(backend): drop uvicorn --reload, run 2 workers in compose

Production runs were on the dev --reload single-worker config. The frontend
fans out ~15 parallel API calls on first paint (folders/tree, tags, heaps,
sharing/*, stats, photos, worker-status, scan/status); they all serialized
on one event loop and felt slow. Switch to 2 workers without --reload for
real concurrency. --proxy-headers preserved client IPs through nginx.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -58,7 +58,7 @@ services:
     # then Alembic runs migrations for existing installs. On fresh DBs
     # create_all already built the full schema, so bootstrap.py stamps
     # alembic head to skip redundant ALTER statements.
-    command: sh -c "python -c 'import asyncio; from app.database import init_db; asyncio.run(init_db())' && python bootstrap.py && uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload"
+    command: sh -c "python -c 'import asyncio; from app.database import init_db; asyncio.run(init_db())' && python bootstrap.py && uvicorn app.main:app --host 0.0.0.0 --port 8000 --workers 2 --proxy-headers"
     environment:
       - DATABASE_URL=postgresql+asyncpg://mulita:mulita@db:5432/mulita
       - REDIS_URL=redis://redis:6379