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

## 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:

<img width="1112" height="191" alt="Screenshot 2026-04-19 115642"
src="https://github.com/user-attachments/assets/c0a169f5-bbd9-4f5d-9474-e4c3795110e4"
/>

## After

`event: "schedule"` correctly returned for scheduled runs:

<img width="890" height="166" alt="Screenshot 2026-04-19 121723"
src="https://github.com/user-attachments/assets/860e99ac-0935-4a43-86a1-7b60f8113480"
/>


## 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.

---------

Co-authored-by: Nicolas <bircni@icloud.com>

models/fixtures/action_run.yml

@@ -89,7 +89,7 @@
   ref: "refs/heads/test"
   commit_sha: "c2d72f548424103f01ee1dc02889c1e2bff816b0"
   event: "push"
-  trigger_event: "push"
+  trigger_event: "schedule"
   is_fork_pull_request: 0
   status: 1
   started: 1683636528

services/convert/action_test.go

@@ -8,8 +8,10 @@ import (
 	"strings"
 	"testing"
 
+	actions_model "code.gitea.io/gitea/models/actions"
 	repo_model "code.gitea.io/gitea/models/repo"
 	"code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/models/unittest"
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/git/gitcmd"
 	"code.gitea.io/gitea/modules/util"
@@ -107,3 +109,18 @@ func TestGetActionWorkflow_FallbackRef(t *testing.T) {
 		assert.ErrorIs(t, err, util.ErrNotExist)
 	})
 }
+
+func TestToActionWorkflowRun_UsesTriggerEvent(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	repo := unittest.AssertExistsAndLoadBean(t, &repo_model.Repository{ID: 2})
+	run := unittest.AssertExistsAndLoadBean(t, &actions_model.ActionRun{ID: 803})
+
+	// Scheduled runs keep Event as the registration event (push) and use TriggerEvent as the real trigger.
+	run.Event = "push"
+	run.TriggerEvent = "schedule"
+
+	apiRun, err := ToActionWorkflowRun(t.Context(), repo, run)
+	require.NoError(t, err)
+	assert.Equal(t, "schedule", apiRun.Event)
+}

services/convert/convert.go

@@ -260,7 +260,7 @@ func ToActionWorkflowRun(ctx context.Context, repo *repo_model.Repository, run *
 		RunNumber:    run.Index,
 		StartedAt:    run.Started.AsLocalTime(),
 		CompletedAt:  run.Stopped.AsLocalTime(),
-		Event:        string(run.Event),
+		Event:        run.TriggerEvent,
 		DisplayTitle: run.Title,
 		HeadBranch:   git.RefName(run.Ref).BranchName(),
 		HeadSha:      run.CommitSHA,

tests/integration/workflow_run_api_check_test.go

@@ -44,6 +44,10 @@ func testAPIWorkflowRunBasic(t *testing.T, apiRootURL, userUsername string, runI
 	foundRun := false
 
 	for _, run := range runnerList.Entries {
+		if run.ID == 802 {
+			// Fixture stores registration event (push) and schedule as trigger; API must expose the trigger as Event.
+			assert.Equal(t, "schedule", run.Event)
+		}
 		// Verify filtering works
 		verifyWorkflowRunCanbeFoundWithStatusFilter(t, apiRunsURL, token, run.ID, "", run.Status, "", "", "", "")
 		verifyWorkflowRunCanbeFoundWithStatusFilter(t, apiRunsURL, token, run.ID, run.Conclusion, "", "", "", "", "")