feat: Update Claude model references from v3 to v4 (fixes issue #118) (#119)

* feat: Update Claude model references from v3 to v4

- Update model configurations from claude-3-opus to claude-4-opus
- Update model configurations from claude-3-sonnet to claude-4-sonnet
- Maintain backward compatibility through existing aliases (opus, sonnet, claude)
- Update provider registry preferred models list
- Update all test cases and assertions to reflect new model names
- Update documentation and examples consistently across all files
- Add Claude 4 model support while preserving existing functionality

Files modified: 15 (config, docs, providers, tests, tools)
Pattern: Systematic claude-3-* → claude-4-* model reference migration

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* PR feedback: changed anthropic/claude-4-opus -> anthropic/claude-opus-4 and anthropic/claude-4-haiku -> anthropic/claude-3.5-haiku

* changed anthropic/claude-4-sonnet -> anthropic/claude-sonnet-4

* PR feedback removed specific model from test mock

* PR feedback removed base.py

---------

Co-authored-by: Omry Nachman <omry@wix.com>
Co-authored-by: Claude <noreply@anthropic.com>

tests/test_per_tool_model_defaults.py

@@ -288,11 +288,11 @@ class TestProviderHelperMethods:
         with patch.object(ModelProviderRegistry, "get_provider") as mock_get_provider:
             # Mock openrouter provider
             mock_openrouter = MagicMock()
-            mock_openrouter.validate_model_name.side_effect = lambda m: m == "anthropic/claude-3.5-sonnet"
+            mock_openrouter.validate_model_name.side_effect = lambda m: m == "anthropic/claude-sonnet-4"
             mock_get_provider.side_effect = lambda ptype: mock_openrouter if ptype == ProviderType.OPENROUTER else None
 
             model = ModelProviderRegistry._find_extended_thinking_model()
-            assert model == "anthropic/claude-3.5-sonnet"
+            assert model == "anthropic/claude-sonnet-4"
 
     def test_find_extended_thinking_model_none_found(self):
         """Test when no thinking model is found."""