feat(safety): enhance rate limiting and cost control with alert deduplication and usage tracking

- Added `record_action` in `RateLimiter` for precise tracking of slot consumption post-validation.
- Introduced deduplication mechanism for warning alerts in `CostController` to prevent spamming.
- Refactored `CostController`'s session and daily budget alert handling for improved clarity.
- Implemented test suites for `CostController` and `SafetyGuardian` to validate changes.
- Expanded integration testing to cover deduplication, validation, and loop detection edge cases.

backend/tests/services/mcp/test_client_manager.py

@@ -20,13 +20,13 @@ from app.services.mcp.routing import ToolInfo, ToolResult
 
 
 @pytest.fixture
-def reset_registry():
+async def reset_registry():
     """Reset the singleton registry before and after each test."""
     MCPServerRegistry.reset_instance()
-    reset_mcp_client()
+    await reset_mcp_client()
     yield
     MCPServerRegistry.reset_instance()
-    reset_mcp_client()
+    await reset_mcp_client()
 
 
 @pytest.fixture
@@ -388,7 +388,8 @@ class TestModuleLevelFunctions:
                 mock_shutdown.return_value = None
                 await shutdown_mcp_client()
 
-    def test_reset_mcp_client(self, reset_registry):
+    @pytest.mark.asyncio
+    async def test_reset_mcp_client(self, reset_registry):
         """Test resetting the global client."""
-        reset_mcp_client()
+        await reset_mcp_client()
         # Should not raise