refactor(frontend, build): update PingViewModel initialization, resolve view model via Koin, and clean yarn dependencies

Injected `PingViewModel` via Koin to align with dependency injection best practices. Suppressed Gradle deprecation warnings and added the `frontend.core.sync` dependency. Cleaned up outdated packages in `yarn.lock`.

core/core-domain/src/commonMain/kotlin/at/mocode/core/sync/Syncable.kt

@@ -0,0 +1,17 @@
+package at.mocode.core.sync
+
+/**
+ * Shared sync contract for all platforms.
+ *
+ * IMPORTANT: This lives in core (not frontend) so that `:contracts:*` can depend on it.
+ */
+interface Syncable {
+  /** Eindeutige ID der Entität (UUID/UUIDv7 als String). */
+  val id: String
+
+  /**
+   * Letzter Änderungszeitpunkt der Entität.
+   * Konvention: `Long` (epoch millis) oder ein kompatibler, monotoner Zeitstempel.
+   */
+  val lastModified: Long
+}