chore(frontend): refactor navigation and DI setup, remove unused shared module

- Replaced `initKoin` with `startKoin` for DI initialization consistency across platforms.
- Introduced `StateNavigationPort` with `StateFlow` to streamline navigation state management.
- Migrated `AppScreen` to sealed class with route mapping for better navigation handling.
- Deleted unused `frontend/shared` module and removed related dependencies from build files.
- Cleaned up legacy navigation and Redux-related code, aligning with MVVM architecture.

frontend/core/navigation/src/commonMain/kotlin/at/mocode/clients/shared/navigation/AppScreen.kt

@@ -1,10 +0,0 @@
-package at.mocode.clients.shared.navigation
-
-sealed class AppScreen {
-  data object Landing : AppScreen()
-  data object Home : AppScreen()
-  data object Login : AppScreen()
-  data object Ping : AppScreen()
-  data object Profile : AppScreen()
-  data object AuthCallback : AppScreen()
-}

frontend/core/navigation/src/commonMain/kotlin/at/mocode/frontend/core/navigation/AppScreen.kt

@@ -0,0 +1,24 @@
+package at.mocode.frontend.core.navigation
+
+sealed class AppScreen(val route: String) {
+  data object Landing : AppScreen(Routes.HOME)
+  data object Home : AppScreen("/home")
+  data object Login : AppScreen(Routes.LOGIN)
+  data object Ping : AppScreen("/ping")
+  data object Profile : AppScreen("/profile")
+  data object AuthCallback : AppScreen("/auth/callback")
+
+  companion object {
+    fun fromRoute(route: String): AppScreen {
+      return when (route) {
+        Routes.HOME -> Landing
+        "/home" -> Home
+        Routes.LOGIN, Routes.Auth.LOGIN -> Login
+        "/ping" -> Ping
+        "/profile" -> Profile
+        "/auth/callback" -> AuthCallback
+        else -> Landing // Default fallback
+      }
+    }
+  }
+}

frontend/core/navigation/src/commonMain/kotlin/at/mocode/frontend/core/navigation/DeepLinkHandler.kt

@@ -28,7 +28,7 @@ class DeepLinkHandler(
   private fun processDeepLink(deepLink: DeepLink): Boolean {
     val route = cleanRoute(deepLink.route)
 
-    // If route requires auth and user is missing → redirect to login
+    // If the route requires auth and the user is missing → redirect to log in
     if (requiresAuth(route)) {
       val user = currentUserProvider.getCurrentUser()
       if (user == null) {