feat: unify email/SMS settings with Bark style (no total toggle)

- Remove emailForwardingEnabled / smsFallbackEnabled total toggles
- Email/SMS SectionCards now use headerAction + CompactStopOnFirstSwitch
  (matching Bark and ntfy)
- Sender logic: email/sms participation controlled solely by per-item
  enabled checkboxes (empty list = channel inactive)
- version 1.8.4 -> 1.8.5 (code 21 -> 22)

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 = 21
-        versionName = "1.8.4"
+        versionCode = 22
+        versionName = "1.8.5"
     }
 
     signingConfigs {