feat: Update Claude models to Opus 4.1 and Sonnet 4.1

This commit updates all references to Claude Opus 4 and Sonnet 4 to their newer 4.1 versions throughout the codebase.

The changes include:
- Updating model names in `conf/custom_models.json` and `providers/dial.py`.
- Updating aliases and descriptions to match the new model versions.
- Updating `.env.example` to reflect the new model names.
- Updating all relevant test suites to use the new model names and ensure all tests pass.

tools/shared/base_tool.py

@@ -1401,7 +1401,7 @@ When recommending searches, be specific about what information you need and why
                 "content": (
                     f"Image support not available: Model '{model_name}' does not support image processing. "
                     f"Please use a vision-capable model such as 'gemini-2.5-flash', 'o3', "
-                    f"or 'claude-3-opus' for image analysis tasks."
+                    f"or 'claude-opus-4.1' for image analysis tasks."
                 ),
                 "content_type": "text",
                 "metadata": {