feat: email forwarding via SMTPS

Parallel to Bark: when email forwarding is enabled and a recipient is set,
notifications are also sent via SMTP over SSL (port 465, SMTPS). Works
standalone — no Bark server required.

- core/EmailSender: SMTP over SSL (implicit TLS, port 465), AUTH LOGIN,
  UTF-8 subject/body via Base64/MIME; trySend() fire-and-forget helper
- SettingsStore: 7 email settings (enabled, host, port, user, password,
  from, to)
- NotifyListenerService + PhoneCallMonitor: call EmailSender.trySend in
  parallel with Bark forwarding; fires even if no Bark servers configured
- UI: new "电邮转发" SectionCard in settings (toggle + host/port/user/
  password/from/to fields + save button)
- version 1.6.0 -> 1.6.1 (code 10 -> 11); CLAUDE.md synced

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/build.gradle.kts

@@ -13,8 +13,8 @@ android {
         applicationId = "com.a2i.forwarder"
         minSdk = 34
         targetSdk = 36
-        versionCode = 10
-        versionName = "1.6.0"
+        versionCode = 11
+        versionName = "1.6.1"
     }
 
     signingConfigs {