feat: execute post run cleanup when workflow is cancelled (#37275)

## Fixes #36983

## Summary
1. Add transitional `Cancelling` status (between `Running` and
`Cancelled`); cancel flow marks active tasks `Cancelling`, runner
finalizes to `Cancelled` on terminal result.
2. Taskless jobs cancel directly (no runner to finalize).
3. Runner-protocol responses map `Cancelling` → `RESULT_CANCELLED`.
4. Run/job aggregation treats `Cancelling` as active.
5. Status mapping/aggregation tests + en-US locale added.

**Problem**
When a workflow was cancelled from the UI, jobs were marked cancelled
immediately, which could skip post-run cleanup behavior.

## Solution
Use a transitional status path:
Running → Cancelling → Cancelled
This allows runner finalization and cleanup path execution before final
terminal state.

**Testing**

> 1. go test -tags "sqlite sqlite_unlock_notify" ./models/actions -run
"TestAggregateJobStatus|TestStatusAsResult|TestStatusFromResult"
> 2. go run
github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.11.4 run
./models/actions/... ./routers/api/actions/runner/...

## Related
- act_runner: https://gitea.com/gitea/act_runner/pulls/825 —
independent; this PR's capability gate keeps legacy runners on the
immediate-cancel path. The new flow activates only for runners that
advertise the `cancelling` capability.

Co-authored-by: Nicolas <bircni@icloud.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>

tests/integration/actions_concurrency_test.go

@@ -1560,6 +1560,9 @@ jobs:
 		// run2 is blocked because it is blocked by workflow1's concurrency group "test-group"
 		assert.Equal(t, actions_model.StatusBlocked, run2.Status)
 
+		// complete wf1-job1
+		runner.execTask(t, w1j1Task, &mockTaskOutcome{result: runnerv1.Result_RESULT_SUCCESS})
+
 		// mock time
 		fakeNow := now.Add(setting.Actions.AbandonedJobTimeout)
 		timeutil.MockSet(fakeNow)