feat(ai): Add Amazon Bedrock provider (#494)

Adds support for Amazon Bedrock with Claude models including:
- Full streaming support via Converse API
- Reasoning/thinking support for Claude models
- Cross-region inference model ID handling
- Multiple AWS credential sources (profile, IAM keys, API keys)
- Image support in messages and tool results
- Unicode surrogate sanitization

Also adds 'Adding a New Provider' documentation to AGENTS.md and README.

Co-authored-by: nickchan2 <nickchan2@users.noreply.github.com>

packages/ai/package.json

@@ -23,6 +23,7 @@
 	},
 	"dependencies": {
 		"@anthropic-ai/sdk": "0.71.2",
+		"@aws-sdk/client-bedrock-runtime": "^3.966.0",
 		"@google/genai": "1.34.0",
 		"@mistralai/mistralai": "1.10.0",
 		"@sinclair/typebox": "^0.34.41",
@@ -39,6 +40,7 @@
 		"openai",
 		"anthropic",
 		"gemini",
+		"bedrock",
 		"unified",
 		"api"
 	],