Add email channel: IMAP IDLE inbound, SMTP outbound, thread matching

Inbound mail on support@top-sysops.ru creates/updates tickets in realtime
(IMAP IDLE, not polling). Replies thread via In-Reply-To/References against
stored Message-IDs, falling back to the customer's open ticket. Mailbox
credentials configured and encrypted via Settings -> Почта, same pattern as
the Telegram channel. TLS verification is opt-in-skippable per mailbox
(mail.top-sysops.ru's cert is currently expired; LAN-only server).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QcXH24ky6zjk2UyK5oZUPH

package.json

@@ -18,8 +18,11 @@
     "better-sqlite3": "^12.11.1",
     "drizzle-orm": "^0.45.2",
     "framer-motion": "^12.4.7",
+    "imapflow": "^1.5.0",
     "lucide-react": "^0.545.0",
+    "mailparser": "^3.9.14",
     "next": "16.2.12",
+    "nodemailer": "^9.0.3",
     "react": "19.2.4",
     "react-dom": "19.2.4",
     "telegraf": "^4.16.3",
@@ -28,7 +31,9 @@
   "devDependencies": {
     "@tailwindcss/postcss": "^4.1.16",
     "@types/better-sqlite3": "^7.6.13",
+    "@types/mailparser": "^3.4.6",
     "@types/node": "^20",
+    "@types/nodemailer": "^8.0.1",
     "@types/react": "^19",
     "@types/react-dom": "^19",
     "drizzle-kit": "^0.31.10",