feat(FN-2523): add safe restart restore lifecycle diagnostics

- Add ProjectEngine restore lifecycle core to perform safe restarts and surface detailed restore state transitions
- Expose restore diagnostics through remote-access status types and settings/memory route context, including legacy API mapping updates
- Add comprehensive regression coverage for restore lifecycle behavior in engine and dashboard headless remote-access tests
- Document the restore lifecycle contract in architecture/settings docs and include a patch changeset for @runfusion/fusion

packages/engine/src/index.ts

@@ -102,6 +102,9 @@ export {
   type TunnelProviderAdapter,
   type TunnelProviderConfig,
   type TunnelReadinessEvent,
+  type TunnelRestoreDiagnostics,
+  type TunnelRestoreOutcome,
+  type TunnelRestoreReasonCode,
   type TunnelStatusListener,
   type TunnelStatusSnapshot,
 } from "./remote-access/index.js";