feat(overlay-sync): wire OverlaySyncService into DI, IPC and renderer gating

packages/application/ports/IOverlaySyncPort.ts

@@ -0,0 +1,7 @@
+export type OverlayAction = { id: string; label: string; meta?: Record<string, unknown>; timeoutMs?: number }
+export type ActionAck = { id: string; status: 'confirmed' | 'tentative' | 'failed'; reason?: string }
+
+export interface IOverlaySyncPort {
+  startAction(action: OverlayAction): Promise<ActionAck>
+  cancelAction(actionId: string): Promise<void>
+}