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>

tools/shared/base_tool.py

@@ -448,7 +448,7 @@ class BaseTool(ABC):
                 except Exception:
                     description += (
                         " OpenRouter: Any model available on openrouter.ai "
-                        "(e.g., 'gpt-4', 'claude-3-opus', 'mistral-large')."
+                        "(e.g., 'gpt-4', 'claude-4-opus', 'mistral-large')."
                     )
             description += f" Defaults to '{DEFAULT_MODEL}' if not specified."