feat(actions): add job summaries (GITHUB_STEP_SUMMARY) (#37500)

- Add GitHub-style Actions **job summaries** support
(`GITHUB_STEP_SUMMARY` / `workflow/SUMMARY.md`) and render them on the
run Summary view.
- Store uploaded summaries internally in the DB (not as downloadable
artifacts).
- Add runtime-token endpoint for runners to upload summaries:
- `PUT
/api/actions_pipeline/_apis/pipelines/workflows/{run_id}/jobs/{job_id}/summary`
- Advertise support to runners via `RunnerService.Declare` response
header:
  - `X-Gitea-Actions-Capabilities: job-summary`
- Devtest: extend `/devtest/repo-action-view/...` to include mock
`jobSummaries` for previewing UI rendering.

## Compatibility
- New Gitea + old runner: no summary upload → UI shows nothing (no
behavior change)
- New runner + old Gitea: capability not advertised → runner skips
upload (no behavior change)

## Screenshot:

<img width="2017" height="729"
src="https://github.com/user-attachments/assets/31f8b945-50c4-40e1-9f40-382901a53013"
/>


Fixes #23721
PR on gitea-runner https://gitea.com/gitea/runner/pulls/917

---------

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>

templates/repo/actions/view_component.tmpl

@@ -15,6 +15,7 @@
 		data-locale-runs-pushed-by="{{ctx.Locale.Tr "actions.runs.pushed_by"}}"
 		data-locale-summary="{{ctx.Locale.Tr "actions.runs.summary"}}"
 		data-locale-all-jobs="{{ctx.Locale.Tr "actions.runs.all_jobs"}}"
+		data-locale-job-summaries="{{ctx.Locale.Tr "actions.runs.job_summaries"}}"
 		data-locale-expand-caller-jobs="{{ctx.Locale.Tr "actions.runs.expand_caller_jobs"}}"
 		data-locale-collapse-caller-jobs="{{ctx.Locale.Tr "actions.runs.collapse_caller_jobs"}}"
 		data-locale-triggered-via="{{ctx.Locale.Tr "actions.runs.triggered_via"}}"