feat(FN-832): add event-driven scheduling on task unpause and auto-resume in-progress tasks

- Auto-resume in-progress tasks that were paused and then unpaused, picking up from their last step
- Add event-driven scheduler trigger on task unpause so resumed tasks are immediately scheduled
- Update Store and TaskStore with unpause handling, type changes for resume tracking
- Refactor executor, merger, and scheduler tests for improved reliability
- Remove dead code: mission-interview, pr-comment-handler, taskStuck util, OpenRouter model sync changeset
- Update AGENTS.md documentation for pause/unpause behavior

agents/agent-0ed51810.json

@@ -0,0 +1,9 @@
+{
+  "id": "agent-0ed51810",
+  "name": "Test",
+  "role": "custom",
+  "state": "idle",
+  "createdAt": "2026-04-04T06:19:55.901Z",
+  "updatedAt": "2026-04-04T06:19:55.901Z",
+  "metadata": {}
+}