feat(claude-local): add Bedrock model selection support

Previously, --model was completely skipped for Bedrock users, so the
model dropdown selection was silently ignored and the CLI always used
its default model.  Selecting Haiku would still run Opus.

- Add listClaudeModels() that returns Bedrock-native model IDs
  (us.anthropic.*) when Bedrock env is detected
- Register listModels on claude_local adapter so the UI dropdown
  shows Bedrock models instead of Anthropic API names
- Allow --model to pass through when the ID is a Bedrock-native
  identifier (us.anthropic.* or ARN)
- Add isBedrockModelId() helper shared by execute.ts and test.ts

Follows up on #2793 which added basic Bedrock auth detection.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/adapters/claude-local/src/server/index.ts

@@ -1,5 +1,6 @@
 export { execute, runClaudeLogin } from "./execute.js";
 export { listClaudeSkills, syncClaudeSkills } from "./skills.js";
+export { listClaudeModels } from "./models.js";
 export { testEnvironment } from "./test.js";
 export {
   parseClaudeStreamJson,