feat: add Claude Sonnet 4.5 support with global cross-region inference (#180)

This commit adds comprehensive support for Claude Sonnet 4.5 (claude-sonnet-4-5-20250929),
Anthropic's most intelligent model with enhanced coding capabilities and complex agent support.

Changes:
- Added global cross-region inference profile discovery (global.anthropic.*)
- Fixed temperature/topP compatibility for Claude Sonnet 4.5 (model doesn't support both simultaneously)
- Fixed reasoning_effort parameter handling to prevent KeyError
- Added extended thinking/interleaved thinking support via extra_body parameter
- Updated documentation with Claude Sonnet 4.5 examples (English and Chinese)
- Updated README with Sonnet 4.5 announcement

Technical Details:
- src/api/models/bedrock.py: Added global profile support in list_bedrock_models()
- src/api/models/bedrock.py: Added Claude Sonnet 4.5 detection to remove topP parameter
- src/api/models/bedrock.py: Changed pop("topP") to pop("topP", None) to prevent KeyError
- docs/Usage.md: Added Chat Completions section with Sonnet 4.5 examples
- docs/Usage.md: Updated Interleaved thinking section with Sonnet 4.5 examples
- docs/Usage_CN.md: Added Chinese versions of all Sonnet 4.5 documentation

Model ID: global.anthropic.claude-sonnet-4-5-20250929-v1:0

README.md

@@ -4,7 +4,9 @@ OpenAI-compatible RESTful APIs for Amazon Bedrock
 
 ## What's New 🔥
 
-This project supports reasoning for both **Claude 3.7 Sonnet** and **DeepSeek R1**, check [How to Use](./docs/Usage.md#reasoning) for more details. You need to first run the Models API to refresh the model list.
+This project now supports **Claude Sonnet 4.5**, Anthropic's most intelligent model with enhanced coding capabilities and complex agent support, available via global cross-region inference.
+
+It also supports reasoning for both **Claude 3.7 Sonnet** and **DeepSeek R1**. Check [How to Use](./docs/Usage.md#reasoning) for more details. You need to first run the Models API to refresh the model list.
 
 ## Overview