Fix LlamaCppConnector.get_model_identity() wrong field names

Same bug as OllamaConnector (C1): hidden_size -> hidden_dim,
removed vocab_size (not a ModelIdentity field). Found by /audit-docs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: SStas

src/avp/connectors/llamacpp.py

@@ -1102,13 +1102,12 @@ def _project_rosetta(self, hidden: Any, source: "LlamaCppConnector") -> Any:
 
     # --- EngineConnector ABC implementation ---
 
-    def get_model_identity(self) -> Any:
+    def get_model_identity(self) -> "ModelIdentity":
         from ..types import ModelIdentity
         return ModelIdentity(
             model_id=self._model_path,
-            hidden_size=self._n_embd,
+            hidden_dim=self._n_embd,
             num_layers=self._n_layer or 0,
-            vocab_size=self._n_vocab,
         )
 
     def extract_hidden_state(self, input_ids, attention_mask=None, past_key_values=None):