feat(bedrock): Integrate AWS Bedrock as a new LLM provider

Adds support for using models hosted on AWS Bedrock, specifically Anthropic Claude models.

Key changes:
- Added '@aws-sdk/client-bedrock-runtime' dependency.
- Updated constants, server config, and auth logic for Bedrock.
- Implemented backend API handler () to communicate with the Bedrock API, handling streaming and non-streaming responses, and formatting output to be OpenAI compatible.
- Updated dynamic API router () to dispatch requests to the Bedrock handler.
- Created frontend client () and updated client factory ().
- Updated  with necessary Bedrock environment variables (AWS keys, region, enable flag) and an example for using  to alias Bedrock models.

package.json

@@ -21,6 +21,7 @@
     "test:ci": "node --no-warnings --experimental-vm-modules $(yarn bin jest) --ci"
   },
   "dependencies": {
+    "@aws-sdk/client-bedrock-runtime": "^3.782.0",
     "@fortaine/fetch-event-source": "^3.0.6",
     "@hello-pangea/dnd": "^16.5.0",
     "@modelcontextprotocol/sdk": "^1.0.4",