feat(FN-4898): reconcile task title-id drift in storage migrations

Adds a title-id drift detection and reconciliation system to prevent duplicate tasks when task titles change after initial creation. Core adds the `task-title-id-drift.ts` module with `markTitleIdStable` and `resolveTitleIdDrift` logic, wired through `db.ts`, `store.ts`, and `archive-db.ts`, with co

Fusion-Task-Id: FN-4898

plugins/fusion-plugin-roadmap/src/store/__tests__/roadmap-store.test.ts

@@ -743,8 +743,8 @@ describe("RoadmapStore", () => {
   });
 
   describe("schema version", () => {
-    it("schema version is 83 after init", () => {
-      expect(db.getSchemaVersion()).toBe(83);
+    it("schema version is 84 after init", () => {
+      expect(db.getSchemaVersion()).toBe(84);
     });
   });