fix(whatsapp): add timeout to fetchLatestBaileysVersion to prevent permanent disconnect wedge

[JonthanaHanh]

Summary

Fixes #77268

The WhatsApp bridge can get permanently disconnected after a server-side disconnect (stream:error 503) when the reconnect path calls fetchLatestBaileysVersion() — a plain fetch() to raw.githubusercontent.com with no timeout. If the connection stalls, the fetch hangs forever. The bridge logs "Reconnecting in 3s..." once then goes silent; the Express server keeps serving 503 to the gateway indefinitely (observed for 27+ hours in the field).

Root Cause

Two issues in scripts/whatsapp-bridge/bridge.js:

1. fetchLatestBaileysVersion() has no timeout — it's a plain fetch() to raw.githubusercontent.com that can hang indefinitely on network stalls. No AbortSignal is passed and no Promise.race wraps it.

2. setTimeout(startSocket, 3000) creates an unhandled promise rejection — startSocket() is async, so calling it from setTimeout returns a promise that's never .catch()-ed. On modern Node.js, unhandled rejections are fatal.

Changes

• Add fetchWithTimeout() helper that races an async function against a configurable timeout (default 15s, overridable via WHATSAPP_VERSION_FETCH_TIMEOUT_MS env var)
• Wrap fetchLatestBaileysVersion() in fetchWithTimeout() so stalled version fetches fail fast instead of hanging forever
• Wrap all startSocket() call sites with .catch() to prevent unhandled promise rejections (fatal on modern Node.js)

Test Plan

• node --check scripts/whatsapp-bridge/bridge.js passes
• Verified reconnect path handles timeout gracefully (manual test with simulated network stall)

[kshitijk4poor]

Closing as duplicate of #77337 (salvage of #77270 by the same author @ATran28). The salvage PR is the more complete version — includes cached version fallback, reconnect error handling with retry, and 6 regression tests. Your fetchWithTimeout approach was simpler but added a WHATSAPP_VERSION_FETCH_TIMEOUT_MS env var which conflicts with the project's .env-is-for-secrets-only policy. Thanks for the contribution!