feat: add infrastructure status to health endpoint

backend/app/routes.py

@@ -421,7 +421,8 @@ def _log_audit(
 
 # Health check
 @router.get("/health", response_model=HealthResponse)
-def health_check(
+async def health_check(
+    request: Request,
     db: Session = Depends(get_db),
     storage: S3Storage = Depends(get_storage),
 ):
@@ -449,11 +450,30 @@ def health_check(
 
     overall_status = "ok" if (storage_healthy and database_healthy) else "degraded"
 
-    return HealthResponse(
-        status=overall_status,
-        storage_healthy=storage_healthy,
-        database_healthy=database_healthy,
-    )
+    # Build response with optional infrastructure status
+    response_data = {
+        "status": overall_status,
+        "storage_healthy": storage_healthy,
+        "database_healthy": database_healthy,
+    }
+
+    # Add HTTP pool status if available
+    if hasattr(request.app.state, 'http_client'):
+        http_client = request.app.state.http_client
+        response_data["http_pool"] = {
+            "pool_size": http_client.pool_size,
+            "worker_threads": http_client.executor_max,
+        }
+
+    # Add cache status if available
+    if hasattr(request.app.state, 'cache'):
+        cache = request.app.state.cache
+        response_data["cache"] = {
+            "enabled": cache.enabled,
+            "connected": await cache.ping() if cache.enabled else False,
+        }
+
+    return HealthResponse(**response_data)
 
 
 # --- Authentication Routes ---