test: update tests to match new Claude Sonnet 4.5 alias configuration

- Updated sonnet alias to point to claude-sonnet-4.5 instead of 4.1
- Removed references to deprecated 'claude' alias
- Added sonnet4.1 alias for claude-sonnet-4.1 backwards compatibility
- All 809 tests passing

tests/test_openrouter_registry.py

@@ -89,7 +89,7 @@ class TestOpenRouterModelRegistry:
         test_cases = [
             ("opus", "anthropic/claude-opus-4.1"),
             ("OPUS", "anthropic/claude-opus-4.1"),  # Case insensitive
-            ("claude", "anthropic/claude-sonnet-4.1"),
+            ("sonnet", "anthropic/claude-sonnet-4.5"),
             ("o3", "openai/o3"),
             ("deepseek", "deepseek/deepseek-r1-0528"),
             ("mistral", "mistralai/mistral-large-2411"),