Initial Flutter-Projekt-Setup (AP0)

Grundgerüst für die Emergency-App: Flutter-Projekt für Android/iOS,
Kern-Packages (url_launcher, geolocator, geocoding, permission_handler,
provider, shared_preferences, intl), Ordnerstruktur laut docs/plan.md
und l10n-Grundgerüst.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

android/build.gradle.kts

@@ -0,0 +1,24 @@
+allprojects {
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+val newBuildDir: Directory =
+    rootProject.layout.buildDirectory
+        .dir("../../build")
+        .get()
+rootProject.layout.buildDirectory.value(newBuildDir)
+
+subprojects {
+    val newSubprojectBuildDir: Directory = newBuildDir.dir(project.name)
+    project.layout.buildDirectory.value(newSubprojectBuildDir)
+}
+subprojects {
+    project.evaluationDependsOn(":app")
+}
+
+tasks.register<Delete>("clean") {
+    delete(rootProject.layout.buildDirectory)
+}