Add a dedicated DagRunType for asset materializations

[guan404ming]

Body

Currently, the materialize_asset API route (POST /assets/{asset_id}/materialize) creates a DagRunType.MANUAL dag run. This means asset materializations are treated as manual runs and are subject to the same allowed_run_types check.

This may not be the right semantic fit. A dag author might want to deny manual triggers but still allow materializations (or vice versa).

We should consider adding a dedicated DagRunType.ASSET_MATERIALIZATION so that:

• Authors can independently control whether their DAG accepts materialization runs vs. manual triggers via allowed_run_types.
• Materialization runs are distinguishable from manual runs in the UI, logs, and audit trail.

Related PR discussion: #61833 (comment)
Parent issue: #61710

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.