feat: integrate Tatlock agent with PydanticAI and Ollama

Convert Tatlock from mock to real PydanticAI agent:
- Connect to Ollama backend (mistral-nemo:latest)
- British butler personality with research-oriented mindset
- Lazy initialization pattern for better testability
- Register permanent tools (calculator, date/time, search)
- Streaming response support with reasoning output
- Error handling for PydanticAI exceptions
- Update registry tests for tools capability
- Add integration test for streaming functionality

tests/agents/test_registry.py

@@ -22,7 +22,7 @@ async def test_list_models():
     # Check model IDs
     model_ids = [m["id"] for m in models]
     assert "lorem-tester" in model_ids
-    assert "tatlock" in model_ids
+    assert "Tatlock" in model_ids
 
     # Check structure
     for model in models:
@@ -57,16 +57,16 @@ async def test_lorem_tester_capabilities():
 async def test_tatlock_capabilities():
     """Test tatlock model capabilities."""
     models = await ModelRegistry.list_models()
-    tatlock_model = next(m for m in models if m["id"] == "tatlock")
+    tatlock_model = next(m for m in models if m["id"] == "Tatlock")
 
     capabilities = tatlock_model["capabilities"]
 
-    # Tatlock is placeholder - minimal capabilities
+    # Tatlock Phase 1 - basic streaming, reasoning, and permanent tools
     assert capabilities["streaming"] is True
-    assert capabilities["reasoning"] is False  # Not yet
-    assert capabilities["tools"] is False      # Not yet
-    assert capabilities["vision"] is False
-    assert capabilities["audio"] is False
+    assert capabilities["reasoning"] is True   # Basic reasoning summaries
+    assert capabilities["tools"] is True       # Permanent tools: calculator, date/time, search
+    assert capabilities["vision"] is False     # Future
+    assert capabilities["audio"] is False      # Future
 
 
 @pytest.mark.unit
@@ -80,7 +80,7 @@ def test_get_agent_lorem_tester():
 @pytest.mark.unit
 def test_get_agent_tatlock():
     """Test getting tatlock agent instance."""
-    agent = ModelRegistry.get_agent("tatlock")
+    agent = ModelRegistry.get_agent("Tatlock")
 
     assert isinstance(agent, TatlockAgent)
 
@@ -98,7 +98,7 @@ def test_get_agent_not_found():
 def test_model_exists():
     """Test checking if model exists."""
     assert ModelRegistry.model_exists("lorem-tester") is True
-    assert ModelRegistry.model_exists("tatlock") is True
+    assert ModelRegistry.model_exists("Tatlock") is True
     assert ModelRegistry.model_exists("nonexistent") is False