fix(FN-690): fix migration schema, dashboard type guards, and test stability

- Fix SQL parameter mismatch in db-migrate task INSERT (add baseCommitSha, modifiedFiles, sliceId columns)
- Fix dashboard routes type predicate to guard against null entries from git diff parsing
- Stabilize central-core activity cleanup test with fake timers
- Align executor test assertions with updated steering comment log messages
- Align store test comment log assertion with new action/outcome format

packages/core/src/store.test.ts

@@ -1587,7 +1587,7 @@ Task with acceptance criteria
       const task = await createTestTask();
       const updated = await store.addComment(task.id, "Comment with log");
 
-      expect(updated.log.some((l) => l.action === "Comment added by user")).toBe(true);
+      expect(updated.log.some((l) => l.action === "Comment added" && l.outcome === "by user")).toBe(true);
     });
 
     it("updates updatedAt timestamp", async () => {