refactor(ocr): rename _contains to contains in SenderModelRegistry

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

ocr-service/engines/kraken.py

@@ -72,7 +72,7 @@ class _SenderModelRegistry:
         with self._lock:
             return len(self._cache)
 
-    def _contains(self, model_path: str) -> bool:
+    def contains(self, model_path: str) -> bool:
         with self._lock:
             return model_path in self._cache
 

ocr-service/test_sender_registry.py

@@ -43,7 +43,7 @@ def test_lru_eviction_removes_least_recently_used():
 
     assert registry.size() == 2
     # 'a' was the least-recently-used and should be gone
-    assert not registry._contains("/app/models/sender_a.mlmodel")
+    assert not registry.contains("/app/models/sender_a.mlmodel")
 
 
 def test_invalidate_removes_entry_from_cache():