audit week 1: creator ID tracking, channel-queue migration, deprecation cleanup

QUAL-006  store ticket.creatorId on creation; legacy split-pop returned the
          message ID for discord-msg-* tickets, breaking transcript DM, close
          log, and channel rename for context-menu-created tickets. Adds the
          field to the Ticket schema and writes a one-shot backfill script
          (scripts/backfill-creatorId.js, dry-run by default).

QUEUE-001 add enqueueOverwrite + enqueueTopic to services/channelQueue.js
          (chain on renameChains alongside enqueueMove). Migrate handleAdd /
          handleRemove / handleMove / handleTopic so permissionOverwrites,
          setParent, and setTopic no longer race pending renames or sends.
          handleMove now uses the existing enqueueMove. Initial overwrites in
          handleTicketModal stay inline; channel doesn't exist yet so no race.

DISCORD-001 replace ephemeral: true with flags: MessageFlags.Ephemeral across
            broccolini-discord.js, handlers/sharedHelpers.js, handlers/buttons.js,
            handlers/commands.js. runDeferred opts now take { flags } directly.

SEC-003   /gmailpoll min interval is 30s. Drop the 5s/10s slash-command
          choices and clamp Math.max(30000, ms) in handleGmailPoll for
          defense in depth.

QUAL-001  upgrade silent .catch(() => {}) on the lastActivity updateOne in
          handlers/messages.js to log via logError, so transient Mongo errors
          surface in the debug channel instead of disappearing.

QUAL-002  drop await from logError/logWarn calls in services/staffThread.js
          and services/pinMessage.js — fire-and-forget per CLAUDE.md hard rule.

QUAL-003  wrap stray setTimeouts (handleConfirmCloseRequest force-close timer,
          runFinalClose channel-delete + overflow-cleanup, checkAutoClose
          delete-after-email) in trackTimeout via lazy require so they clear
          on shutdown.

services/channelQueue.js

@@ -113,6 +113,81 @@ function enqueueMove(channel, categoryId) {
   return next;
 }
 
+// Shares renameChains so a permissionOverwrite mutation serializes with pending
+// renames/moves on the same channel. Mode 'create' calls
+// `channel.permissionOverwrites.create(id, perms)`; 'delete' calls
+// `channel.permissionOverwrites.delete(id)`. No coalescing.
+function enqueueOverwrite(channel, id, perms, mode = 'create') {
+  let entry = renameChains.get(channel.id);
+  if (!entry) {
+    entry = { chain: Promise.resolve(), pendingName: null };
+    renameChains.set(channel.id, entry);
+  }
+
+  const next = entry.chain.catch(() => {}).then(() =>
+    mode === 'delete'
+      ? channel.permissionOverwrites.delete(id)
+      : channel.permissionOverwrites.create(id, perms)
+  );
+  entry.chain = next;
+
+  next.catch((err) => {
+    logWarn('overwriteQueue', `Overwrite ${mode} failed for ${channel.name}: ${err && err.message || err}`).catch(() => {});
+    const status = err && err.status;
+    const msg = (err && err.message) || String(err);
+    if (status === 401 || status === 403) {
+      logError(
+        'overwriteQueue:token/permission',
+        new Error(`${status} channel=${channel.id} target=${id} mode=${mode}: ${msg}`)
+      ).catch(() => {});
+    } else if (status === 429) {
+      logError(
+        'overwriteQueue:ratelimited',
+        new Error(`429 channel=${channel.id} target=${id} mode=${mode}: ${msg}`)
+      ).catch(() => {});
+    }
+  }).finally(() => {
+    if (renameChains.get(channel.id) === entry && entry.chain === next && entry.pendingName == null) {
+      renameChains.delete(channel.id);
+    }
+  });
+  return next;
+}
+
+// Shares renameChains so setTopic serializes with pending renames/moves.
+function enqueueTopic(channel, text) {
+  let entry = renameChains.get(channel.id);
+  if (!entry) {
+    entry = { chain: Promise.resolve(), pendingName: null };
+    renameChains.set(channel.id, entry);
+  }
+
+  const next = entry.chain.catch(() => {}).then(() => channel.setTopic(text));
+  entry.chain = next;
+
+  next.catch((err) => {
+    logWarn('topicQueue', `Topic set failed for ${channel.name}: ${err && err.message || err}`).catch(() => {});
+    const status = err && err.status;
+    const msg = (err && err.message) || String(err);
+    if (status === 401 || status === 403) {
+      logError(
+        'topicQueue:token/permission',
+        new Error(`${status} channel=${channel.id}: ${msg}`)
+      ).catch(() => {});
+    } else if (status === 429) {
+      logError(
+        'topicQueue:ratelimited',
+        new Error(`429 channel=${channel.id}: ${msg}`)
+      ).catch(() => {});
+    }
+  }).finally(() => {
+    if (renameChains.get(channel.id) === entry && entry.chain === next && entry.pendingName == null) {
+      renameChains.delete(channel.id);
+    }
+  });
+  return next;
+}
+
 // Per-channel promise chain for send ordering and to prevent interleaving.
 const sendChains = new Map();
 
@@ -157,4 +232,4 @@ function enqueueDelete(channel) {
   return next;
 }
 
-module.exports = { enqueueRename, enqueueMove, enqueueSend, enqueueDelete };
+module.exports = { enqueueRename, enqueueMove, enqueueOverwrite, enqueueTopic, enqueueSend, enqueueDelete };