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/discord/commands/index.js

@@ -0,0 +1,31 @@
+// Command registry. Each module exports { data, execute } — `data` is the
+// slash-command definition pushed to Discord (registerCommands), `execute` is
+// the interactionCreate handler (dispatch). Adding a new command is just
+// adding a file here — discordManager.js never needs to change.
+const commands = [
+  require('./ping.command'),
+  require('./modlog.command'),
+  require('./ban.command'),
+  require('./kick.command'),
+  require('./mute.command'),
+  require('./warn.command'),
+  require('./warnings.command'),
+  require('./filter.command'),
+  require('./filterallow.command'),
+  require('./schedule.command'),
+  require('./rolemenu.command'),
+  require('./autorole.command'),
+  require('./role.command'),
+  require('./roles.command'),
+  require('./invite.command'),
+  require('./news.command'),
+  require('./announce.command'),
+  require('./wiki.command'),
+]
+
+const byName = new Map(commands.map((c) => [c.data.name, c]))
+
+module.exports = {
+  all: commands,
+  get: (name) => byName.get(name),
+}