Gmail folder auto-advance + /forward command

- Reply-cycle auto-advance: staff reply files the thread to "Awaiting Reply",
  a customer response files it to "Needs Response" (new GMAIL_LABEL_AWAITING_REPLY
  / GMAIL_LABEL_NEEDS_RESPONSE labels + autoAdvanceFolder, which only moves
  threads still in the auto-cycle and leaves hand-filed folders alone)
- /forward: forward a ticket's email to another address (handlers/commands/forward.js
  + forward composition in services/gmail.js)
- Tests for the auto-advance cycle; label fixtures updated for the new labels

handlers/commands/index.js

@@ -31,6 +31,7 @@ const { runEscalation, runDeescalation, handleEscalate, handleDeescalate, resolv
 const { handleCloseTimer, handleCancelClose, handleForceClose } = require('./close');
 const { handleResponse, handleAutocomplete } = require('./response');
 const { handlePanel, handleSignature } = require('./panel');
+const { handleForward } = require('./forward');
 const { handleCreateTicketFromMessage, handleViewUserTickets } = require('./contextMenu');
 
 const Ticket = mongoose.model('Ticket');
@@ -355,7 +356,7 @@ async function handleHelp(interaction) {
       },
       {
         name: 'Ticket Management',
-        value: '`/transfer @staff [reason]` - Transfer ticket to another staff member\n`/move #category` - Move ticket to another category\n`/force-close` - Force close ticket without confirmation\n`/cancel-close` - Abort a pending force-close countdown\n`/topic <text>` - Set ticket topic/description\n`/folder <destination>` - File this ticket\'s email into a Gmail folder'
+        value: '`/transfer @staff [reason]` - Transfer ticket to another staff member\n`/move #category` - Move ticket to another category\n`/force-close` - Force close ticket without confirmation\n`/cancel-close` - Abort a pending force-close countdown\n`/topic <text>` - Set ticket topic/description\n`/folder <destination>` - File this ticket\'s email into a Gmail folder\n`/forward <email> [note]` - Forward this ticket\'s email thread to another address'
       },
       {
         name: 'Saved Responses',
@@ -405,6 +406,7 @@ const COMMAND_HANDLERS = {
   email: handleEmail,
   folder: handleFolder,
   closetimer: handleCloseTimer,
+  forward: handleForward,
   'cancel-close': handleCancelClose,
   'force-close': handleForceClose,
   topic: handleTopic,