feat(FN-4538): complete Step 1 — add overlapBlockedBy persistence

Fusion-Task-Id: FN-4538
Fusion-Task-Lineage: 332b4c78-b67f-45d0-9181-0bb539b662c1

packages/core/src/db.ts

@@ -119,7 +119,7 @@ export function probeFts5(db: DatabaseSync): boolean {
 
 // ── Schema Definition ────────────────────────────────────────────────
 
-const SCHEMA_VERSION = 78;
+const SCHEMA_VERSION = 79;
 
 function normalizeTaskComments(
   steeringComments: SteeringComment[] | undefined,
@@ -194,6 +194,7 @@ CREATE TABLE IF NOT EXISTS tasks (
   currentStep INTEGER DEFAULT 0,
   worktree TEXT,
   blockedBy TEXT,
+  overlapBlockedBy TEXT,
   paused INTEGER DEFAULT 0,
   userPaused INTEGER DEFAULT 0,
   pausedReason TEXT,
@@ -3284,6 +3285,12 @@ export class Database {
       });
     }
 
+    if (version < 79) {
+      this.applyMigration(79, () => {
+        this.addColumnIfMissing("tasks", "overlapBlockedBy", "TEXT");
+      });
+    }
+
   }
 
   /**