feat: interactive inline buttons, SMTP reply, AI reply suggestions

- Inline keyboard: view original / back to summary toggle per message
- SMTP config per account for sending replies
- Reply button: click, type message, auto-send via SMTP
- AI Reply button: generates 3 suggestions via DeepSeek
  - Simple replies (OK, Got it) send immediately on tap
  - Substantive replies require confirm before send
  - Hides AI Reply button when AI determines reply unnecessary
- Telegram long polling integrated into main loop for real-time interaction

config.yaml.example

@@ -3,11 +3,19 @@ email_accounts:
     imap_port: 993
     username: "your_email@gmail.com"
     password: "your_app_password"
+    smtp:
+      server: "smtp.gmail.com"
+      port: 465
+      use_ssl: true
 
-  - imap_server: "imap.qq.com"
+  - imap_server: "imap.126.com"
     imap_port: 993
-    username: "your_email@qq.com"
-    password: "your_authorization_code"
+    username: "your_email@126.com"
+    password: "your_auth_code"
+    smtp:
+      server: "smtp.126.com"
+      port: 465
+      use_ssl: true
 
 ai:
   api_key: "sk-your_deepseek_api_key"