chore(config): simplify dependabot configuration and disable enhanced services for CPU-only deployment

- Simplify .github/dependabot.yml from 70 to 49 lines
  - Remove beta ecosystems, custom registries, and detailed ignore rules
  - Reduce open PR limits (npm: 10→5, github-actions: 5→3)
  - Remove custom labels and dependency-specific ignore rules
  - Consolidate npm configs from 2 directories to single root directory
  - Remove docker ecosystem configuration

- Add /health endpoint to coordinator

apps/coordinator-api/src/app/routers/marketplace_gpu.py

@@ -163,6 +163,15 @@ async def register_gpu(
     }
 
 
+@router.get("/marketplace/gpus")
+async def list_gpus_cli(
+    session: SessionDep,
+    available: Optional[bool] = Query(default=None),
+):
+    """List GPUs for CLI compatibility."""
+    return await list_gpus(session, available)
+
+
 @router.get("/marketplace/gpu/list")
 async def list_gpus(
     session: SessionDep,