chore(MP-23): network DI client, frontend architecture guards, detekt & ktlint setup, docs, ping DI factory (#21)

* chore(MP-21): snapshot pre-refactor state (Epic 1)

* chore(MP-22): scaffold new repo structure, relocate Docker Compose, move frontend/backend modules, update Makefile; add docs mapping and env template

* MP-22 Epic 2: Erfolgreich umgesetzt und verifiziert

* MP-23 Epic 3: Gradle/Build Governance zentralisieren

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

@@ -0,0 +1,12 @@
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.window.ComposeViewport
+import kotlinx.browser.document
+import org.w3c.dom.HTMLElement
+
+@OptIn(ExperimentalComposeUiApi::class)
+fun main() {
+  val root = document.getElementById("ComposeTarget") as HTMLElement
+  ComposeViewport(root) {
+    MainApp()
+  }
+}