### feat: optimiere Architektur und verbessere E-Mail-Handling

- **ArchTests:** Passe Slices-Matching für `FrontendArchitectureTest` an Package-Struktur an.
- **Mail-Service:** Füge Plan-B-Benachrichtigung für Nennungen an Meldestelle hinzu; entferne Plus-Addressing (Fallback).
- **Build:** Deaktiviere Desktop-Build standardmäßig (`enableDesktop=false`) und mache Module-Registrierung optional.

platform/architecture-tests/build.gradle.kts

@@ -38,6 +38,6 @@ dependencies {
   implementation(projects.frontend.core.localDb)
   implementation(projects.frontend.core.sync)
 
-  implementation(projects.frontend.shells.meldestelleDesktop)
+  // implementation(projects.frontend.shells.meldestelleDesktop) // Temporarily disabled while desktop build is disabled
   // implementation(projects.frontend.shells.meldestelleWeb) // WASM-only modules cannot be tested with ArchUnit (JVM-only)
 }

platform/architecture-tests/src/test/kotlin/at/mocode/archtests/FrontendArchitectureTest.kt

@@ -11,9 +11,9 @@ class FrontendArchitectureTest {
 
   @ArchTest
   fun `feature modules should not depend on each other`(importedClasses: JavaClasses) {
-    // The pattern must match the actual package structure, e.g., 'at.mocode.ping.feature'
+    // The pattern must match the actual package structure, e.g., 'at.mocode.frontend.features.(*)..'
     slices()
-      .matching("at.mocode.(*).feature..")
+      .matching("at.mocode.frontend.features.(*)..")
       .should().notDependOnEachOther()
       .check(importedClasses)
   }