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/utils/oauth/index.ts

@@ -9,9 +9,6 @@
  * - Antigravity (Gemini 3, Claude, GPT-OSS via Google Cloud)
  */
 
-// Set up HTTP proxy for fetch() calls (respects HTTP_PROXY, HTTPS_PROXY env vars)
-import "../http-proxy.js";
-
 // Anthropic
 export { anthropicOAuthProvider, loginAnthropic, refreshAnthropicToken } from "./anthropic.js";
 // GitHub Copilot