fix: resolve ty type error for Lock._loop private attribute

Replace access to private `asyncio.Lock._loop` attribute with equivalent
check using `self.client_loop`, which is semantically equivalent and avoids
the unresolved-attribute diagnostic.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

django/aiservice/aiservice/llm.py

@@ -95,8 +95,8 @@ class LLMClient:
         # try to close/recreate clients simultaneously (Issue #10)
         loop = asyncio.get_running_loop()
 
-        # Create lock for this event loop if it doesn't exist
-        if self._client_lock is None or self._client_lock._loop is not loop:
+        # Create lock for this event loop if it doesn't exist or the loop has changed
+        if self._client_lock is None or loop is not self.client_loop:
             self._client_lock = asyncio.Lock()
 
         if loop is not self.client_loop:

django/aiservice/aiservice/tests/test_llm_client_close.py

@@ -190,6 +190,6 @@ class TestLLMClientClose:
             # Verify that close() was NEVER called
             # The old fix (PR #2548/#2575) would call close() and catch errors
             # The new fix (Issue #11) should not call close() at all
-            assert (
-                mock_client.close.call_count == 0
-            ), f"Client close() was called {mock_client.close.call_count} times. Should be 0 to prevent TOCTOU race."
+            assert mock_client.close.call_count == 0, (
+                f"Client close() was called {mock_client.close.call_count} times. Should be 0 to prevent TOCTOU race."
+            )

django/aiservice/tests/aiservice/test_llm_client.py

@@ -101,9 +101,9 @@ class TestLLMClientEventLoopHandling:
             # requests could use closed clients, leading to RuntimeError
             # New behavior: clients are not closed, allowing GC to clean them up safely
             assert first_openai_client.close.call_count == 0, "Old OpenAI client should not be closed (Issue #11 fix)"
-            assert (
-                first_anthropic_client.close.call_count == 0
-            ), "Old Anthropic client should not be closed (Issue #11 fix)"
+            assert first_anthropic_client.close.call_count == 0, (
+                "Old Anthropic client should not be closed (Issue #11 fix)"
+            )
 
             # Verify new clients were created
             assert client.openai_client is not first_openai_client