feat: v1.9.4 — exit node for ChatGPT/Claude/Grok + drop duplicate Telegram post

Two changes addressing user-reported issues today:

1. Exit-node feature ported from upstream masterking32@464a6e1d, with
   hardening. Cloudflare-protected sites (chatgpt.com, claude.ai,
   grok.com, x.com, openai.com) flag Google datacenter IPs as bots and
   return Turnstile / CAPTCHA / 502 challenges. Apps Script's UrlFetchApp
   exits from those IPs, so v1.9.3 surfaces these as "Relay error: json:
   key must be a string..." with no apps_script-mode workaround.

   Now a small TypeScript HTTP endpoint (assets/exit_node/valtown.ts)
   deployed on val.town / Deno Deploy sits between Apps Script and the
   destination. Chain: client → Apps Script (Google IP) → val.town
   (non-Google IP) → destination. Destination sees val.town's IP, no
   CF challenge.

   Config:
     "exit_node": {
       "enabled": true,
       "relay_url": "https://...web.val.run",
       "psk": "<openssl rand -hex 32>",
       "mode": "selective",
       "hosts": ["chatgpt.com", "claude.ai", "x.com", "grok.com", "openai.com"]
     }

   Hardening over upstream: PSK fail-closed if still placeholder (fresh
   deploy can't be open relay), loop guard (refuses fetch of own host),
   explicit 503 on misconfigured. Fallback to direct Apps Script on exit
   node failure (CF-affected sites fail, others keep working). Setup
   docs in English + Persian at assets/exit_node/README*.md. Example
   config at config.exit-node.example.json.

2. Removed the legacy `telegram` job from release.yml. With
   TELEGRAM_NOTIFY_ENABLED repo var set to true, every release was
   producing two duplicate APK posts on the main Telegram channel: the
   old bundled-APK-on-main job AND the newer per-file files-channel
   posts (telegram-publish-files.yml). Only the per-file flow is wanted.
   Legacy job and its helper telegram_release_notify.py are gone.
   Recoverable from git log if anyone needs the bundled pattern back.

169 mhrv-rs lib tests + 33 tunnel-node tests + UI build clean.

Author: therealaleph