feat(sdm): inject structural dependency mapping tags across codebase

Adds [C: caller] tags to functions/methods and [M: mutation] / [U: usage] tags to class variables based on cross-module call analysis.

tests/test_ai_client_list_models.py

@@ -3,8 +3,9 @@ from src import ai_client
 def test_list_models_gemini_cli() -> None:
  """
  
-     Verifies that 'ai_client.list_models' correctly returns a list of models
-     for the 'gemini_cli' provider.
+  
+      Verifies that 'ai_client.list_models' correctly returns a list of models
+      for the 'gemini_cli' provider.
  """
  models = ai_client.list_models("gemini_cli")
  assert "gemini-3.1-pro-preview" in models