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/models.ts

@@ -0,0 +1,40 @@
+import type { AdapterModel } from "@paperclipai/adapter-utils";
+
+/** Anthropic direct API model IDs — used when Bedrock is not active. */
+const DIRECT_MODELS: AdapterModel[] = [
+  { id: "claude-opus-4-6", label: "Claude Opus 4.6" },
+  { id: "claude-sonnet-4-6", label: "Claude Sonnet 4.6" },
+  { id: "claude-haiku-4-6", label: "Claude Haiku 4.6" },
+  { id: "claude-sonnet-4-5-20250929", label: "Claude Sonnet 4.5" },
+  { id: "claude-haiku-4-5-20251001", label: "Claude Haiku 4.5" },
+];
+
+/** AWS Bedrock model IDs — region-qualified identifiers required by the Bedrock API. */
+const BEDROCK_MODELS: AdapterModel[] = [
+  { id: "us.anthropic.claude-opus-4-6-v1", label: "Bedrock Opus 4.6" },
+  { id: "us.anthropic.claude-sonnet-4-5-20250929-v2:0", label: "Bedrock Sonnet 4.5" },
+  { id: "us.anthropic.claude-haiku-4-5-20251001-v1:0", label: "Bedrock Haiku 4.5" },
+];
+
+function isBedrockEnv(): boolean {
+  return (
+    process.env.CLAUDE_CODE_USE_BEDROCK === "1" ||
+    process.env.CLAUDE_CODE_USE_BEDROCK === "true" ||
+    (typeof process.env.ANTHROPIC_BEDROCK_BASE_URL === "string" &&
+      process.env.ANTHROPIC_BEDROCK_BASE_URL.trim().length > 0)
+  );
+}
+
+/**
+ * Return the model list appropriate for the current auth mode.
+ * When Bedrock env vars are detected, returns Bedrock-native model IDs;
+ * otherwise returns standard Anthropic API model IDs.
+ */
+export async function listClaudeModels(): Promise<AdapterModel[]> {
+  return isBedrockEnv() ? BEDROCK_MODELS : DIRECT_MODELS;
+}
+
+/** Check whether a model ID is a Bedrock-native identifier (not an Anthropic API short name). */
+export function isBedrockModelId(model: string): boolean {
+  return model.startsWith("us.anthropic.") || model.startsWith("arn:aws:bedrock:");
+}