Remove dead/stale code, dedup close+escalation paths

Dead/stale removals (grep-confirmed no consumers):
- config: drop 9 unread CONFIG keys (ROLE_TO_PING_ID, SIGNATURE,
  REMINDER_*, RENAME_LOG_CHANNEL_ID, SETTINGS_*); remove their
  ALLOWED_CONFIG_KEYS entries and the orphaned settings-site UI fields
- configSchema: delete unreachable json/string_or_json validators
- models: drop unused ticketTag field
- gmail-poll: remove unused isPollSuspended export
- utils: remove dead htmlToTextWithBlocks/decodeHtmlEntities/BLOCK_TAG_REGEX
- internalApi: remove router._allowedKeys (test it served is gone)
- discord client: drop unused GuildPresences privileged intent
- broccolini-discord: remove dormant /api 503 gate (no /api routes)

Fixes:
- context-menu ticket create now uses makeTicketName('unclaimed', ...)
  instead of the contract-violating ticket-<n> name
- drop write-only pending.userId from both close paths

Dedup / simplify:
- new services/transcript.js shares the transcript text/date/header
  builders between the button and force-close paths (had drifted)
- resolveEscalationCategoryId() replaces 3 copies of the category logic
- ticketChannelOverwrites() shares the create-permission array between
  the two interactive ticket-create paths
- finalizeBody() shares the email-cleanup tail in parseGmailMessage
- getTicketActionRow drops its never-passed options arg;
  sendTicketNotificationEmail drops its always-null subjectLine arg
- hoist invariant guild lookup out of the auto-close/unclaim loops
- drop redundant lastActivity write (and now-dead updateTicketActivity)
- /help lists all current commands and the right-click apps

services/tickets.js

@@ -1,6 +1,6 @@
 /**
  * Ticket database helpers – counters, rename, limits, auto-close,
- * reminders, auto-unclaim, channel creation.
+ * auto-unclaim, channel creation.
  */
 const { ChannelType } = require('discord.js');
 const { mongoose, withRetry } = require('../db-connection');
@@ -269,15 +269,6 @@ async function checkTicketLimits(senderEmail) {
   return { ok: true };
 }
 
-// --- ACTIVITY ---
-
-async function updateTicketActivity(gmailThreadId) {
-  await Ticket.updateOne(
-    { gmailThreadId },
-    { $set: { lastActivity: new Date() } }
-  );
-}
-
 // --- SCHEDULED CHECKS ---
 // These accept `client` and optionally `sendTicketClosedEmail` to avoid circular deps.
 
@@ -291,11 +282,11 @@ async function checkAutoClose(client, sendTicketClosedEmail) {
     lastActivity: { $lt: cutoffTime, $ne: null }
   }).sort({ createdAt: 1 }).limit(500).lean());
 
+  const guild = client.guilds.cache.first();
+  if (!guild) return;
+
   for (const ticket of staleTickets) {
     try {
-      const guild = client.guilds.cache.first();
-      if (!guild) continue;
-
       const channel = await guild.channels.fetch(ticket.discordThreadId).catch(() => null);
       if (channel) {
         await enqueueSend(channel, CONFIG.DISCORD_AUTO_CLOSE_MESSAGE);
@@ -337,11 +328,11 @@ async function checkAutoUnclaim(client) {
     lastActivity: { $lt: unclaimTime, $ne: null }
   }).lean());
 
+  const guild = client.guilds.cache.first();
+  if (!guild) return;
+
   for (const ticket of staleClaimedTickets) {
     try {
-      const guild = client.guilds.cache.first();
-      if (!guild) continue;
-
       const channel = await guild.channels.fetch(ticket.discordThreadId).catch(() => null);
       if (channel) {
         await withRetry(() => Ticket.updateOne(
@@ -426,7 +417,6 @@ module.exports = {
   makeTicketName,
   checkTicketCreationRateLimit,
   checkTicketLimits,
-  updateTicketActivity,
   checkAutoClose,
   checkAutoUnclaim,
   reconcileDeletedTicketChannels,