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/coding-agent/src/cli/list-models.ts

@@ -25,7 +25,7 @@ function formatTokenCount(count: number): string {
  * List available models, optionally filtered by search pattern
  */
 export async function listModels(modelRegistry: ModelRegistry, searchPattern?: string): Promise<void> {
-	const models = await modelRegistry.getAvailable();
+	const models = modelRegistry.getAvailable();
 
 	if (models.length === 0) {
 		console.log("No models available. Set API keys in environment variables.");