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/coding-agent/src/core/model-registry.ts

@@ -14,11 +14,10 @@ import {
 	type OpenAICompletionsCompat,
 	type OpenAIResponsesCompat,
 	registerApiProvider,
-	registerOAuthProvider,
 	resetApiProviders,
-	resetOAuthProviders,
 	type SimpleStreamOptions,
 } from "@mariozechner/pi-ai";
+import { registerOAuthProvider, resetOAuthProviders } from "@mariozechner/pi-ai/oauth";
 import { type Static, Type } from "@sinclair/typebox";
 import AjvModule from "ajv";
 import { existsSync, readFileSync } from "fs";