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.

build.gradle.kts

@@ -75,7 +75,11 @@ subprojects {
   tasks.withType<KotlinCompile>().configureEach {
     compilerOptions {
       jvmTarget.set(JvmTarget.JVM_25)
-      freeCompilerArgs.add("-Xannotation-default-target=param-property")
+      freeCompilerArgs.addAll(
+        "-opt-in=kotlin.RequiresOptIn",
+        "-Xannotation-default-target=param-property",
+        "-Xexpect-actual-classes",
+      )
     }
   }