fix: propagate rendered_map_index through the reschedule state path

[kalluripradeep]

What's the problem?

TIRescheduleStatePayload was the only intermediate-state payload missing rendered_map_index. As a result, when a mapped sensor sets context["map_index_template"] inside its poke() body and then raises AirflowRescheduleException to reschedule, the rendered_map_index value is never persisted to the database. The UI displays the raw integer map_index (e.g. 0, 1) on every up_for_reschedule row instead of the human-readable rendered label.

The final successful poke does show the rendered label (because the success path already serialises rendered_map_index via TaskState), so the column appears intermittently.

Fixes #67521

Root cause

The full data path for a reschedule is:

sensor.poke()
  ↓ raises AirflowRescheduleException
task_runner.run()
  ↓ except AirflowRescheduleException: builds RescheduleTask(…)   ← missing rendered_map_index
supervisor._handle_requests()
  ↓ client.task_instances.reschedule(id, msg)                      ← msg has no rendered_map_index
execution API PATCH /task-instances/{id}
  ↓ TIRescheduleStatePayload                                       ← model had no field
  ↓ query.values(state=…, next_method=None, next_kwargs=None)      ← _rendered_map_index never written

All other intermediate states (TIDeferredStatePayload, TIAwaitingInputStatePayload, TIRetryStatePayload, TITerminalStatePayload, TISuccessStatePayload) already carry rendered_map_index. The reschedule path was the only one left out.

Note: _render_map_index() is called in the except Exception: block (line ~1576 of task_runner.py) before re-raising AirflowRescheduleException, so ti.rendered_map_index is correctly populated by the time we build RescheduleTask. We only need to pass it through.

Changes

File	Change
airflow-core/…/datamodels/taskinstance.py	Add rendered_map_index: str | None = None to TIRescheduleStatePayload (server-side model)
task-sdk/…/api/datamodels/_generated.py	Same field on the client-side generated model
task-sdk/…/execution_time/task_runner.py	Pass rendered_map_index=ti.rendered_map_index when constructing RescheduleTask
task-sdk/…/execution_time/supervisor.py	Set self._rendered_map_index = msg.rendered_map_index in both RescheduleTask handler branches
airflow-core/…/routes/task_instances.py	Include _rendered_map_index=ti_patch_payload.rendered_map_index in the UP_FOR_RESCHEDULE query
airflow-core/…/versions/v2026_06_30.py	Cadwyn migration AddRenderedMapIndexToReschedulePayload
airflow-core/…/versions/__init__.py	Register the migration in the 2026-06-30 version bundle
task-sdk/tests/…/test_task_runner.py	Regression test test_run_reschedule_includes_rendered_map_index

Testing

New regression test verifies that when a sensor sets map_index_template and rescheduled, the RescheduleTask message carries rendered_map_index:

def test_run_reschedule_includes_rendered_map_index(create_runtime_ti, mock_supervisor_comms):
    ...
    assert msg.rendered_map_index is not None