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/warnings.js

@@ -0,0 +1,26 @@
+// Standing warnings (separate from mod_actions so /warnings can list a
+// user's active warnings). expires_at is always NULL for now — decay/escalation
+// (e.g. "3 active warns -> auto-mute") is deferred past Phase 2, see
+// warn.command.js.
+const db = require('../db')
+
+async function add({ guildId, targetUserId, targetTag, staffUserId, staffTag, reason }) {
+  await db.query(
+    `INSERT INTO warnings (guild_id, target_user_id, target_tag, staff_user_id, staff_tag, reason)
+     VALUES (?, ?, ?, ?, ?, ?)`,
+    [guildId, targetUserId, targetTag || null, staffUserId, staffTag || null, reason || null],
+  )
+}
+
+// Active = not expired. Every row is active today since expires_at is never
+// set, but the query is written to already respect it once decay lands.
+async function listActive(guildId, targetUserId) {
+  return db.query(
+    `SELECT id, reason, staff_tag, created_at FROM warnings
+     WHERE guild_id = ? AND target_user_id = ? AND (expires_at IS NULL OR expires_at > NOW())
+     ORDER BY created_at DESC`,
+    [guildId, targetUserId],
+  )
+}
+
+module.exports = { add, listActive }