chore: refactor Gradle config, standardize Kotlin MPP plugin usage, and update dependencies

- Unified plugin application across modules using `alias(libs.plugins.*)` instead of hardcoded IDs.
- Removed redundant JVM/JS source map tasks, improving Gradle and Docker build consistency.
- Updated dependencies, including `logback` and Webpack `copy-webpack-plugin`, and added contextual documentation.
- Added frontend architecture diagram in PlantUML (`docs/01_Architecture/Reference`), standardizing feature-core-shell dependencies.

frontend/core/navigation/build.gradle.kts

@@ -1,10 +1,8 @@
 /**
  * Dieses Modul definiert nur die Navigationsrouten.
- * Es ist noch simpler.
  */
 plugins {
-  // Fix for "Plugin loaded multiple times": Apply plugin by ID without version (inherited from root)
-  id("org.jetbrains.kotlin.multiplatform")
+  alias(libs.plugins.kotlinMultiplatform)
 }
 
 group = "at.mocode.clients.shared"
@@ -14,18 +12,13 @@ kotlin {
   jvm()
   js {
     binaries.library()
-    // Re-enabled browser environment after Root NodeJs fix
-    browser {
-        testTask {
-            enabled = false
-        }
-    }
+    browser()
   }
 
   sourceSets {
     commonMain.dependencies {
       // Depend on core domain for User/Role types used by navigation API
-      implementation(project(":frontend:core:domain"))
+      implementation(projects.frontend.core.domain)
     }
     commonTest.dependencies {
       implementation(libs.kotlin.test)