chore: api readme

Author: ayushkrtiwari

src/quant_research_starter/api/README.md

@@ -0,0 +1,19 @@
+API backend for QuantResearchStarter
+
+Run the FastAPI app (development):
+
+```bash
+export DATABASE_URL="postgresql+asyncpg://postgres:password@db:5432/qrs"
+export REDIS_URL="redis://redis:6379/0"
+uvicorn src.quant_research_starter.api.main:app --reload --port 8000
+```
+
+Run Celery worker:
+
+```bash
+celery -A src.quant_research_starter.api.tasks.celery_app.celery_app worker --loglevel=info
+```
+
+Notes:
+- This scaffold uses Postgres (asyncpg), Redis (Celery broker + pubsub), and JWT auth.
+- For production, run workers and web app in separate containers/processes, and use Alembic to manage schema migrations.