Add Discord bot (moderation, filters, scheduling, roles, invites, site integration)

Standalone bot/ service (its own package.json/Dockerfile) managed entirely
through a new admin-only Discord Bot panel — token stored encrypted in the
DB and pushed to the bot process in-memory, never an env var. Built in
phases, each independently verified against a live Discord guild:

- Bot skeleton: gateway connection, internal shared-secret API, self-heals
  on its own restart by pulling config from the site
- Moderation core: /ban /kick /mute /warn /warnings + mod-log channel
- Word/invite/spam filtering with leetspeak-resistant normalization and a
  staff role/channel allowlist
- Scheduled messages: recurring (cron) and one-off channel posts
- Role assignment: button role menus, auto-role on join, temp roles,
  bulk role ops
- Auto-rotating primary invite with an audit log
- Site integration: news-publish -> Discord announce webhook, manual
  /announce, read-only /wiki search

Also fixes a pre-existing bug in both DB pools (server + bot): the mariadb
driver defaulted to timezone 'local', silently mis-serializing bound Date
params by the host's local offset instead of the DB's UTC session.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

server/src/router/v1/v1.router.js

@@ -5,9 +5,13 @@ const v1Router = express.Router()
 const authRouter = require('./auth/auth.routes')
 const publicRouter = require('./public/public.routes')
 const adminRouter = require('./admin/admin.routes')
+const internalRouter = require('./internal/internal.routes')
 
 v1Router.use('/auth', authRouter)
 v1Router.use('/public', publicRouter)
 v1Router.use('/admin', adminRouter)
+// Shared-secret gated (not session-gated) — server<->bot only, never exposed
+// through the public reverse proxy. See server/src/middleware/requireInternalKey.js.
+v1Router.use('/internal', internalRouter)
 
 module.exports = v1Router