fix: use TriggerEvent instead of Event in workflow runs API response for scheduled runs (#37288)

[GiteaBot]

Backport #37288 by @KalashThakare

Summary

Fixes #37252

The /api/v1/repos/{owner}/{repo}/actions/runs endpoint was returning
event: "push" for workflow runs triggered by schedule: (cron), instead
of event: "schedule".

Root Cause

ActionRun has two separate fields:

• Event — the workflow registration event (e.g. push, set when the workflow file was first pushed)
• TriggerEvent — the actual event that triggered the run (e.g. schedule)

ToActionWorkflowRun in services/convert/action.go was serializing
run.Event into the API response instead of run.TriggerEvent, causing
scheduled runs to be indistinguishable from push events via the API.

This was already asymmetric — the tasks/jobs API correctly used TriggerEvent.

Fix

Changed ToActionWorkflowRun to use run.TriggerEvent for the event
field in the API response, consistent with how the jobs API works.

Before

event: "push" returned for all scheduled runs:

After

event: "schedule" correctly returned for scheduled runs:

Testing

• Added unit test TestToActionWorkflowRun_UsesTriggerEvent in
  services/convert/action_test.go that explicitly verifies the API
  returns TriggerEvent and not Event for a scheduled run.
• Manually verified via the API against a live Gitea instance with a
  cron: "* * * * *" workflow.