feat(app): scaffolding initial du projet Flutter GameTime

Structure Flutter iOS/Android (lib/ organisé en couches domain,
application, infrastructure, presentation), intégration Drift pour la
persistance locale (sqlite3_flutter_libs), configuration des plateformes
android/ et ios/. Build APK debug validé.

Ajuste le .gitignore pour ignorer l'état d'exécution IdeA
(.ideai/permissions.json) au même titre que le reste du runtime.

Co-Authored-By: Claude Opus 4.8 <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)
+}