feat: ntfy forwarding support

Parallel push channel alongside Bark and email: POST {server}/{topic}
with optional Bearer auth. Same fire-and-forget pattern as email.

- core/NtfySender: OkHttp PUT to ntfy; retry 3x on IOException
- SettingsStore: ntfyEnabled/server/topic/token (default server ntfy.sh)
- NotifyListenerService + PhoneCallMonitor: NtfySender.trySend after bark
- UI: "ntfy 转发" SectionCard (Bark → ntfy → Email → SMS)
- version 1.6.2 -> 1.7.0 (code 12 -> 13)

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 = 12
-        versionName = "1.6.2"
+        versionCode = 13
+        versionName = "1.7.0"
     }
 
     signingConfigs {