fix: correct Docker setup, SDK async API, and docs

- Dockerfile: use explicit uvicorn command (uv run start fails without package mode)
- docker-compose: mount claude-auth volume to /root/.claude (worker runs as root)
- worker: update to Claude Code SDK async iterable API (query() returns iterator, not array)
- main.py: fix docs_url from /doc to /docs
- README: correct login instructions (exec not run --rm), add production URLs
- Add CLAUDE.md with full project documentation

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

src/backend/main.py

@@ -35,7 +35,7 @@ async def lifespan(app: FastAPI):
 app = FastAPI(
     title="OpusAgent",
     version="0.1.0",
-    docs_url="/doc",
+    docs_url="/docs",
     redoc_url="/redoc",
     openapi_url="/openapi.json",
     lifespan=lifespan,