feat: dynamic model list via browser-captured ListModels RPC

[CharoenwitKunna]

Problem

The model list is hardcoded in configs/models.json (currently 30 models). When Google adds new models (e.g. gemini-3.7-flash, robotics-er-2-preview), users must manually edit this file and restart the server.

Additionally, the generativelanguage.googleapis.com/v1beta/models endpoint returns 403 API_KEY_SERVICE_BLOCKED when called from the browser context, making direct model discovery unreliable.

Proposed Solution

Auto-fetch the model list at runtime from the same ListModels RPC endpoint that the AI Studio app calls on page load, via page.on('response') capture in BrowserManager.

Key changes:

• BrowserManager: hook page.on('response') before page.goto to capture the app's own ListModels response + request headers (URL, API key)
• BrowserManager.fetchLiveModels(): return captured models (with configurable TTL), falling back to a manual RPC call using the captured URL/headers
• BrowserManager._parseListModelsResponse(): parse the [[ [...], ... ]] protobuf+JSON array into models.json-compatible objects
• ConfigLoader: add DYNAMIC_MODELS (default true) and DYNAMIC_MODELS_TTL (default 3600000 ms) env vars
• ProxyServerSystem: make GET /v1/models and GET /v1beta/models async, call fetchLiveModels() with static config as fallback
• ProxyServerSystem: add POST /api/models/refresh?persist=true endpoint for manual refresh

Benefits

• No hardcoded domain/key — auto-discovered from the browser's own captured request
• Works even if Google rotates the CoJqbf backend domain or API key
• Zero-config — enabled by default, models update automatically on next request after TTL expires
• Backward compatible — DYNAMIC_MODELS=false reverts to static configs/models.json

Testing

With DYNAMIC_MODELS=true and empty configs/models.json ({"models":[]}):

• Server fetches 36 live models via captured ListModels RPC
• GET /v1beta/models returns all 36 models
• Without capture fallback, auto-detects base URL from page config (CoJqbf) and API key from page scripts

Environment

• Node.js on Windows
• Playwright with Camoufox (Firefox)
• AI Studio Build App with Google account auth