refactor(ping-feature): integrate DI refactor, enhance web build, and update feature workflow

Refactored the `ping-feature` module to adopt centralized `HttpClient` through Koin DI, replacing legacy implementations. Added secure API calls with improved error handling and updated Webpack build scripts to resolve worker path issues. Enhanced `PingScreen` with extended functionality, UI updates, and aligned test cases for the new architecture. Consolidated feature workflows and finalized documentation with a comprehensive feature implementation guide.

frontend/shells/meldestelle-portal/src/jsMain/kotlin/main.kt

@@ -9,7 +9,8 @@ import at.mocode.frontend.core.localdb.localDbModule
 import at.mocode.frontend.core.localdb.DatabaseProvider
 import at.mocode.frontend.core.localdb.AppDatabase
 import at.mocode.frontend.core.sync.di.syncModule
-import at.mocode.ping.feature.di.pingFeatureModule
+import at.mocode.clients.pingfeature.di.pingFeatureModule
+import at.mocode.ping.feature.di.pingSyncFeatureModule
 import navigation.navigationModule
 import kotlinx.coroutines.MainScope
 import kotlinx.coroutines.launch
@@ -30,7 +31,7 @@ fun main() {
   console.log("[WebApp] main() entered")
   // Initialize DI (Koin) with shared modules + network + local DB modules
   try {
-    initKoin { modules(networkModule, localDbModule, syncModule, pingFeatureModule, authFeatureModule, navigationModule) }
+    initKoin { modules(networkModule, localDbModule, syncModule, pingFeatureModule, pingSyncFeatureModule, authFeatureModule, navigationModule) }
     console.log("[WebApp] Koin initialized with networkModule + localDbModule + authFeatureModule + navigationModule")
   } catch (e: dynamic) {
     console.warn("[WebApp] Koin initialization warning:", e)