fix(actions): keep github.event.inputs as strings for workflow_dispatch (#38899)

`github.event.inputs` must mirror the raw `workflow_dispatch` payload,
where
GitHub keeps every input as a string. Only the separate `inputs` context
preserves declared types, e.g. booleans. A previous fix coerced boolean
inputs in the single map that fed both contexts, so
`github.event.inputs.someBool` became a real boolean and comparisons
like
`== 'true'` stopped matching.

`github.event.inputs` now stays string-only again. The `inputs` context
used
for server-side `if:` evaluation of needs-gated/matrix-deferred jobs
re-coerces booleans independently, from the job's own workflow
declaration,
so that path keeps working correctly.

Fixes https://github.com/go-gitea/gitea/issues/38896

---------

Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>

routers/web/repo/actions/actions.go

@@ -760,6 +760,10 @@ type WorkflowDispatchInput struct {
 	Options     []string `yaml:"options"`
 }
 
+func (i WorkflowDispatchInput) IsDefaultTrue() bool {
+	return util.ParseYamlBool(i.Default)
+}
+
 type WorkflowDispatch struct {
 	Inputs []WorkflowDispatchInput
 }