fix(ai,coding-agent): make pi-ai browser-safe and move OAuth runtime exports

- add browser smoke bundling check to root check + pre-commit

- lazy-load Bedrock provider registration to avoid browser graph traversal

- remove top-level OAuth runtime exports from @mariozechner/pi-ai

- add @mariozechner/pi-ai/oauth subpath export and update coding-agent imports

- move proxy dispatcher init to coding-agent CLI (Node-only)

- document Bedrock/OAuth browser limitations

closes #1814

packages/ai/src/index.ts

@@ -16,7 +16,16 @@ export * from "./stream.js";
 export * from "./types.js";
 export * from "./utils/event-stream.js";
 export * from "./utils/json-parse.js";
-export * from "./utils/oauth/index.js";
+export type {
+	OAuthAuthInfo,
+	OAuthCredentials,
+	OAuthLoginCallbacks,
+	OAuthPrompt,
+	OAuthProvider,
+	OAuthProviderId,
+	OAuthProviderInfo,
+	OAuthProviderInterface,
+} from "./utils/oauth/types.js";
 export * from "./utils/overflow.js";
 export * from "./utils/typebox-helpers.js";
 export * from "./utils/validation.js";