fix(server): throttle the cost-bearing proxies by default

The OpenAI endpoints (/api/realtime/token, /api/openai/hud-summary) now
allow 30 requests per minute per client IP and the Google Places endpoints
120, the caps the Pinokio build already ships. GEV_RATELIMIT_OPENAI_PER_MIN
and GEV_RATELIMIT_GOOGLE_PER_MIN still override them and exactly 0 disables
them; an unreadable value falls back to the default rather than to
unlimited.

Salvaged from #683 onto current main.

Co-authored-by: Sameh Khamis <[email protected]>
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

SECURITY.md

@@ -80,7 +80,7 @@ The dev server is a **key broker**: every server-side key above is spendable by
 
 - **Local-only by default.** `./scripts/dev-fresh.sh` (and the Vite config itself) bind to `localhost`, so only your machine can reach the server — and only local names are accepted (`allowedHosts` stays restricted, which also blunts DNS-rebinding tricks).
 - **LAN exposure is an explicit opt-in**: `HOST=0.0.0.0 ./scripts/dev-fresh.sh`. The launcher prints a prominent warning plus your LAN URL. Understand what opting in means: **every device on that network can drive the proxies and spend your OpenAI / Google / OpenSky / AISStream / TomTom / FIRMS quota** for as long as the server runs. Do this only on networks you trust.
-- **App-level throttles (opt-in):** `GEV_RATELIMIT_OPENAI_PER_MIN` and `GEV_RATELIMIT_GOOGLE_PER_MIN` cap the cost-bearing endpoints per client IP per minute (over-limit requests receive a sanitized `429`). They are **per-IP, process-local, in-memory guards** — they reset on restart and are **not billing caps**.
+- **App-level throttles (on by default):** `GEV_RATELIMIT_OPENAI_PER_MIN` (default `30`) and `GEV_RATELIMIT_GOOGLE_PER_MIN` (default `120`) — the values the Pinokio build already ships — cap the cost-bearing endpoints per client IP per minute (over-limit requests receive a sanitized `429`). Both defaults sit well above what the app itself generates; set either to exactly `0` to run unthrottled. They are **per-IP, process-local, in-memory guards** — they reset on restart, a caller with several addresses gets a bucket per address, and they are **not billing caps**.
 - **Provider-side budgets are the real backstop.** For hard spend protection, configure limits where the money is: OpenAI platform usage limits, Google Cloud budget alerts + per-API quotas, and equivalent controls for any other keyed provider.
 - **Pinokio LAN and Cloudflare sharing are refused.** The current supported
   Pinokio release re-reads sharing state when an app registers its Open URL and