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>

bot/src/model/inviteLog.js

@@ -0,0 +1,29 @@
+const db = require('../db')
+
+async function record({ guildId, channelId, inviteCode, triggeredBy, triggeredByTag }) {
+  const res = await db.query(
+    `INSERT INTO invite_log (guild_id, channel_id, invite_code, triggered_by, triggered_by_tag)
+     VALUES (?, ?, ?, ?, ?)`,
+    [guildId, channelId, inviteCode, triggeredBy || null, triggeredByTag || null],
+  )
+  return res.insertId
+}
+
+// The active (not-yet-revoked) invite for a guild, if any.
+async function getCurrent(guildId) {
+  const rows = await db.query(
+    'SELECT * FROM invite_log WHERE guild_id = ? AND revoked_at IS NULL ORDER BY created_at DESC LIMIT 1',
+    [guildId],
+  )
+  return rows[0] || null
+}
+
+async function markRevoked(id) {
+  await db.query('UPDATE invite_log SET revoked_at = NOW() WHERE id = ?', [id])
+}
+
+async function list(guildId, limit = 10) {
+  return db.query('SELECT * FROM invite_log WHERE guild_id = ? ORDER BY created_at DESC LIMIT ?', [guildId, limit])
+}
+
+module.exports = { record, getCurrent, markRevoked, list }