simplify: prune dead code, dedup gmail send, drop neutered log stubs

- Remove no-op log stubs (logGmail, logAutomation, logSecurity, logSystem)
  and ~17 callsites; dead counters in tickets.js and gmail-poll.js go too
- Dedup three near-identical Gmail send paths into sendThreadedEmail helper
- Drop dead Mongoose fields: broccoliniTicketId, lastSyncedBroccoliniArticleId,
  renameCount, renameWindowStart, reminderSent, staffChannelId,
  unclaimedRemindersSent, lastMessageAuthorIsStaff
- Drop dead config fields and their .env.example entries
- Inline api/botClient.js (3-line wrapper, 2 callers)
- Trim unused exports across utils.js, tickets.js, configSchema.js, debugLog.js
- Fix handlers/messages.js to use isStaff() — old partial check ignored
  ADDITIONAL_STAFF_ROLES, so those members were treated as customers
- Drop unused deps p-queue + dotenv-expand; move mongodb to devDependencies

Net: -583 LOC source + -57 LOC lockfile. All 23 modules load clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

models.js

@@ -5,8 +5,6 @@ var mongoose = require('mongoose');
 const ticketSchema = new mongoose.Schema({
     gmailThreadId: { type: String, required: true, unique: true, index: true },
     discordThreadId: String,
-    broccoliniTicketId: Number,
-    lastSyncedBroccoliniArticleId: Number,
     senderEmail: { type: String, required: true },
     subject: String,
     createdAt: { type: Date, default: Date.now },
@@ -16,18 +14,12 @@ const ticketSchema = new mongoose.Schema({
     escalated: { type: Boolean, default: false },
     escalationTier: { type: Number, default: 0 },
     ticketNumber: Number,
-    renameCount: { type: Number, default: 0 },
-    renameWindowStart: Date,
     priority: { type: String, default: 'normal', enum: ['low', 'normal', 'medium', 'high'] },
     ticketTag: String,
     lastActivity: Date,
-    reminderSent: { type: Boolean, default: false },
     welcomeMessageId: String,
     claimerId: String,
-    staffChannelId: String,
     parentCategoryId: String,
-    unclaimedRemindersSent: { type: [Number], default: [] },
-    lastMessageAuthorIsStaff: { type: Boolean, default: false },
     pendingDelete: { type: Boolean, default: false }
 });
 ticketSchema.index({ status: 1, lastActivity: 1 });