fix(ceo-approve): require substantive notes; panel collects them

ceo-approve was bound to QANotes (notes required), so the panel's
one-click approve (posts {}) 422'd. The wrong fix is to waive notes —
that empties the audit record for a production merge. Instead require
substantive notes (>=20 chars, mirroring pass-qa) and make the panel
COLLECT them: a new CeoApproveDialog (mirrors the reject dialog) gates
the 'Approve & Merge' action, and the dashboard approval-queue enforces
the same before POSTing. The CEO sign-off note is now always captured.

tests/integration/test_tasks_routes.py

@@ -2434,7 +2434,7 @@ async def test_ceo_approve_service_returns_none(ceo_client: dict) -> None:
     await ceo_client["db"].flush()
     response = await ceo_client["client"].post(
         f"/api/tasks/{task.id}/ceo-approve",
-        json={"notes": "approved"},
+        json={"notes": "Reviewed and approved for production release."},
         headers=_HDR,
     )
     assert response.status_code == HTTPStatus.BAD_REQUEST
@@ -2452,12 +2452,31 @@ async def test_ceo_approve_success(ceo_client: dict) -> None:
         mock_factory.return_value = instance
         response = await ceo_client["client"].post(
             f"/api/tasks/{task.id}/ceo-approve",
-            json={"notes": "approved"},
+            json={"notes": "Verified against all acceptance criteria; approved."},
             headers=_HDR,
         )
     assert response.status_code == HTTPStatus.OK
 
 
+@pytest.mark.asyncio
+async def test_ceo_approve_without_notes_rejected(ceo_client: dict) -> None:
+    """Audit: a CEO approval with no/thin notes leaves no record of WHY the
+    work shipped, so the endpoint must reject it (>= 20 chars required). The
+    panel collects the note before POSTing."""
+    task = _seed_task_ceo(ceo_client)
+    await ceo_client["db"].flush()
+    for body in ({}, {"notes": ""}, {"notes": "lgtm"}):
+        response = await ceo_client["client"].post(
+            f"/api/tasks/{task.id}/ceo-approve",
+            json=body,
+            headers=_HDR,
+        )
+        assert response.status_code in (
+            HTTPStatus.BAD_REQUEST,
+            HTTPStatus.UNPROCESSABLE_ENTITY,
+        ), (body, response.status_code)
+
+
 @pytest.mark.asyncio
 async def test_ceo_reject_task_not_found(ceo_client: dict) -> None:
     response = await ceo_client["client"].post(