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

gmail-poll.js

@@ -37,7 +37,6 @@ function setPollSuspended(val) {
   pollSuspended = !!val;
   if (!pollSuspended) authErrorNotified = false;
 }
-function isPollSuspended() { return pollSuspended; }
 
 // ============================================================
 // Helpers (extracted from the original 309-line poll()).
@@ -73,6 +72,16 @@ function locateGuild(client) {
  *   - followupBody: defensive — strip quotes but fall back to raw text if
  *     stripping leaves nothing. Used for follow-up posts on an existing thread.
  */
+// Shared final cleanup for both the first-message and follow-up body paths:
+// drop the "Get Outlook for ..." mobile-signature line, strip a dangling
+// trailing "<" left by truncated HTML, and trim.
+function finalizeBody(text) {
+  return text
+    .replace(/Get Outlook for [^\n]+/gi, '')
+    .replace(/<\s*$/gm, '')
+    .trim();
+}
+
 function parseGmailMessage(email) {
   const headers = email.data.payload.headers;
   const from = headers.find(h => h.name === 'From')?.value || '';
@@ -92,10 +101,7 @@ function parseGmailMessage(email) {
   firstBody = stripMobileFooter(firstBody);
   firstBody = firstBody.replace(/^\s*\n+/g, '');
   firstBody = firstBody.replace(/\n{3,}/g, '\n\n');
-  firstBody = firstBody
-    .replace(/Get Outlook for [^\n]+/gi, '')
-    .replace(/<\s*$/gm, '')
-    .trim();
+  firstBody = finalizeBody(firstBody);
 
   const rawText = rawBody.replace(/\r\n/g, '\n');
   let followupBody = stripEmailQuotes(rawText);
@@ -103,10 +109,7 @@ function parseGmailMessage(email) {
   followupBody = followupBody.replace(/^\s*\n*/, '\n');
   followupBody = followupBody.replace(/\n{3,}/g, '\n\n');
   followupBody = stripMobileFooter(followupBody);
-  followupBody = followupBody
-    .replace(/Get Outlook for [^\n]+/gi, '')
-    .replace(/<\s*$/gm, '')
-    .trim();
+  followupBody = finalizeBody(followupBody);
 
   return {
     isSelf,
@@ -405,4 +408,4 @@ async function poll(client) {
   }
 }
 
-module.exports = { poll, setPollSuspended, isPollSuspended };
+module.exports = { poll, setPollSuspended };