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/scheduledMessages.js

@@ -0,0 +1,57 @@
+const db = require('../db')
+
+async function addRecurring({ guildId, channelId, content, cronExpression, createdBy, createdByTag }) {
+  const res = await db.query(
+    `INSERT INTO scheduled_messages (guild_id, channel_id, content, cron_expression, created_by, created_by_tag)
+     VALUES (?, ?, ?, ?, ?, ?)`,
+    [guildId, channelId, content, cronExpression, createdBy || null, createdByTag || null],
+  )
+  return res.insertId
+}
+
+async function addOnce({ guildId, channelId, content, runAt, createdBy, createdByTag }) {
+  const res = await db.query(
+    `INSERT INTO scheduled_messages (guild_id, channel_id, content, run_at, created_by, created_by_tag)
+     VALUES (?, ?, ?, ?, ?, ?)`,
+    [guildId, channelId, content, runAt, createdBy || null, createdByTag || null],
+  )
+  return res.insertId
+}
+
+// Returns true if a row was actually removed (scoped to the guild so one
+// guild can't remove another's rows).
+async function remove(guildId, id) {
+  const res = await db.query('DELETE FROM scheduled_messages WHERE id = ? AND guild_id = ?', [id, guildId])
+  return Number(res.affectedRows || 0) > 0
+}
+
+async function list(guildId) {
+  return db.query(
+    `SELECT id, channel_id, content, cron_expression, run_at, enabled, sent_at FROM scheduled_messages
+     WHERE guild_id = ? ORDER BY id ASC`,
+    [guildId],
+  )
+}
+
+// All enabled recurring rows across every guild the bot serves — v1 only
+// ever has one, but the scheduler doesn't need to special-case that.
+async function listEnabledRecurring() {
+  return db.query(
+    `SELECT id, guild_id, channel_id, content, cron_expression FROM scheduled_messages
+     WHERE cron_expression IS NOT NULL AND enabled = 1`,
+  )
+}
+
+// One-off rows due to post right now.
+async function listDueOneOff() {
+  return db.query(
+    `SELECT id, guild_id, channel_id, content FROM scheduled_messages
+     WHERE run_at IS NOT NULL AND sent_at IS NULL AND enabled = 1 AND run_at <= NOW()`,
+  )
+}
+
+async function markSent(id) {
+  await db.query('UPDATE scheduled_messages SET sent_at = NOW() WHERE id = ?', [id])
+}
+
+module.exports = { addRecurring, addOnce, remove, list, listEnabledRecurring, listDueOneOff, markSent }