fix(actions): exclude workflow_call from workflow trigger detection (#37894) (#37899)

Backport #37894 by @Zettat123

Gitea now only allows `workflow_dispatch.inputs`. If a workflow contains
`workflow_call.inputs`, the workflow cannot be triggered, even though
the `on:` section contains other trigger events.


https://github.com/go-gitea/gitea/blob/428ee9fcce7928bf5405900345d43e9ba1b01564/modules/actions/jobparser/model.go#L402-L405

For example, this workflow cannot be triggered due to
`workflow_call.inputs`:
```yaml
on:
  push:
  pull_request:
  workflow_call:
    inputs:
      name:
        type: string
```

---

This PR is extracted from #37478 for backport

Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.8) <noreply@anthropic.com>

modules/actions/jobparser/model.go

@@ -298,6 +298,9 @@ func toGitContext(input map[string]any) *model.GithubContext {
 	return gitContext
 }
 
+// workflowCallEvent is only fired by another workflow's `uses:`, so it is excluded from trigger detection.
+const workflowCallEvent = "workflow_call"
+
 func ParseRawOn(rawOn *yaml.Node) ([]*Event, error) {
 	switch rawOn.Kind {
 	case yaml.ScalarNode:
@@ -306,6 +309,9 @@ func ParseRawOn(rawOn *yaml.Node) ([]*Event, error) {
 		if err != nil {
 			return nil, err
 		}
+		if val == workflowCallEvent {
+			return []*Event{}, nil
+		}
 		return []*Event{
 			{Name: val},
 		}, nil
@@ -319,6 +325,9 @@ func ParseRawOn(rawOn *yaml.Node) ([]*Event, error) {
 		for _, v := range val {
 			switch t := v.(type) {
 			case string:
+				if t == workflowCallEvent {
+					continue
+				}
 				res = append(res, &Event{Name: t})
 			default:
 				return nil, fmt.Errorf("invalid type %T", t)
@@ -332,6 +341,9 @@ func ParseRawOn(rawOn *yaml.Node) ([]*Event, error) {
 		}
 		res := make([]*Event, 0, len(events))
 		for i, k := range events {
+			if k == workflowCallEvent {
+				continue
+			}
 			v := triggers[i]
 			switch v.Kind {
 			case yaml.ScalarNode: