The /api/messaging/platforms endpoints (catalog, configure, test) shipped
with the desktop app but never got a dashboard UI; the recent admin-panel
PRs covered MCP/webhooks/hooks/system but skipped messaging channels. This
adds the missing page so all 20+ channels (Telegram, Discord, Slack, Matrix,
Mattermost, WhatsApp, Signal, BlueBubbles, Email, SMS, DingTalk, Feishu,
WeCom, WeChat, QQ Bot, Yuanbao, plugin platforms, etc.) can be configured,
enabled/disabled, tested, and connected entirely from the browser.
- web/src/pages/ChannelsPage.tsx: per-platform list with live status, enable
Switch, Test, and a Configure modal that renders each platform's exact
setup fields (secrets masked, required validated, redacted display).
- web/src/lib/api.ts: MessagingPlatform types + get/update/test client fns.
- web/src/App.tsx: /channels route + nav tab (Radio icon, after MCP).
- docs: Channels section + REST endpoints + screenshot.
Frontend-only — reuses the existing env-write + config-enable backend, which
auto-enables a platform once its required env vars are present and the
gateway restarts. No core changes, no new tool schema.