fix(actions): reject jobs without runs-on (#39480)

Align job and `runs-on` validation with github.com, as implemented by
the parser in https://github.com/actions/runner. A job without `runs-on`
could be claimed by any runner, so a job meant for a container could run
on the host.

- Jobs without `runs-on` fail with `Required property is missing:
runs-on`, called workflows included
- Unknown job keys and callers (`uses:`) mixed with steps-only keys like
`runs-on` are rejected
- Empty, null and nested `runs-on` values are rejected
- A `runs-on` evaluating to such a value fails only that job
- Called workflows are validated at run creation, an invalid one fails
the run as an invalid workflow file
- Zero labels (`runs-on: []` or `{}`) never match a runner, including
jobs queued before upgrading

<img width="960" alt="image"
src="https://github.com/user-attachments/assets/e746ce5a-b711-4e8b-aab8-81336ff53d86"
/>

**Behavior Change:** workflows that omit `runs-on`, use unknown job keys
or mix `uses` with `runs-on` stop running until fixed.

---------

Co-authored-by: bircni <bircni@icloud.com>
Co-authored-by: silverwind <me@silverwind.io>

modules/actions/workflows_test.go

@@ -30,18 +30,23 @@ jobs:
 
 func TestReadWorkflowEventsStaticErrors(t *testing.T) {
 	for content, static := range map[string]bool{
-		"on: push\njobs: {}":                                                                  true,
-		"on: push\njobs: {test: {needs: absent}}":                                             true,
-		"on: push\njobs: {one: {needs: two}, two: {needs: one}}":                              true,
-		"on: push\njobs: {test: {strategy: {matrix: {os: []}}}}":                              true,
-		"on: push\nrun-name: ${{ secrets.TOKEN }}\njobs: {test: {}}":                          true,
-		"on: push\nrun-name: ${{ fromJSON(inputs.x) }}\njobs: {test: {steps: [{run: echo}]}}": false,
+		"on: push\njobs: {}": true,
+		"on: push\njobs: {test: {runs-on: x, needs: absent}}":                                             true,
+		"on: push\njobs: {one: {runs-on: x, needs: two}, two: {runs-on: x, needs: one}}":                  true,
+		"on: push\njobs: {test: {runs-on: x, strategy: {matrix: {os: []}}}}":                              true,
+		"on: push\nrun-name: ${{ secrets.TOKEN }}\njobs: {test: {runs-on: x}}":                            true,
+		"on: push\njobs: {test: {steps: [{run: echo}]}}":                                                  true,
+		"on: push\nrun-name: ${{ fromJSON(inputs.x) }}\njobs: {test: {runs-on: x, steps: [{run: echo}]}}": false,
 	} {
 		_, gotStatic, err := readWorkflowEvents([]byte(content))
 		require.Error(t, err, content)
 		assert.Equal(t, static, gotStatic, content)
 	}
-	for _, content := range []string{"on: push\njobs: {test: {steps: [{run: echo}]}}", "on: push\nrun-name: ${{ github.ref }}\njobs: {test: {}}"} {
+	for _, content := range []string{
+		"on: push\njobs: {test: {runs-on: x, steps: [{run: echo}]}}",
+		"on: push\nrun-name: ${{ github.ref }}\njobs: {test: {runs-on: x}}",
+		"on: push\njobs: {call: {uses: ./.gitea/workflows/called.yml}}",
+	} {
 		_, _, err := readWorkflowEvents([]byte(content))
 		assert.NoError(t, err, content)
 	}