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

utils.js

@@ -22,9 +22,6 @@ function isStaff(member) {
 
 // --- TEXT PROCESSING ---
 
-const BLOCK_TAG_REGEX =
-  /<\/(p|div|li|h[1-6]|tr|table|section|article|blockquote)>/gi;
-
 function escapeRegex(str) {
   return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
 }
@@ -40,28 +37,6 @@ function escapeHtml(str) {
     .replace(/'/g, '&#39;');
 }
 
-function decodeHtmlEntities(str) {
-  if (!str) return '';
-  return str
-    .replace(/&amp;/g, '&')
-    .replace(/&lt;/g, '<')
-    .replace(/&gt;/g, '>')
-    .replace(/&quot;/g, '"')
-    .replace(/&#39;/g, "'")
-    .replace(/&nbsp;/g, ' ');
-}
-
-function htmlToTextWithBlocks(html) {
-  return decodeHtmlEntities(
-    html
-      .replace(/\r\n/g, '\n')
-      .replace(/<br\s*\/?>/gi, '\n')
-      .replace(BLOCK_TAG_REGEX, '\n\n')
-      .replace(/<(ul|ol)[^>]*>/gi, '\n')
-      .replace(/<[^>]*>?/gm, '')
-  );
-}
-
 // --- EMAIL BODY EXTRACTION ---
 
 function decodeGmailData(p) {
@@ -277,7 +252,6 @@ module.exports = {
   escapeHtml,
   safeEqual,
   isStaff,
-  htmlToTextWithBlocks,
   getCleanBody,
   stripEmailQuotes,
   stripMobileFooter,