k8s: provision /github dirs per step so container uses:/JS actions get event.json

[DJRH]

Fixes #330. Also supersedes the prepare-time approach in #300, and relates to #337 / #347 (missing /github dirs in novolume).

Problem

In kubernetes-novolume container mode, a containerised uses:/JS-action step that reads the event payload via GITHUB_EVENT_PATH (/github/workflow/event.json) receives an empty payload and fails. For example actions/dependency-review-action errors with a schema-validation failure:

GITHUB_EVENT_PATH /github/workflow/event.json does not exist
##[error][ { "code": "invalid_type", "expected": "object", "received": "undefined", "message": "Required" } ]

run: steps are unaffected because they operate in /__w.

Root cause

This is the regression described in #330. /github/{home,workflow} used to be copied per step in run-script-step.ts (added in #287), but #293 ("Reduce the amount of data copied to the workflow pod") replaced that block with a _temp_pre → _temp merge that only handles _temp and no longer copies _github_home/_github_workflow into /github/.

/github is otherwise provisioned only by:

• prepareJobScript (utils.ts) — once, at prepare-job time, and only when the job declares userMountVolumes.
• writeContainerStepScript (utils.ts) — for Docker container action steps.

Plain run-script / JS-action steps never (re)provision /github. And simply un-gating prepareJobScript (as in #300) is not sufficient: the runner stages event.json into _work/_temp/_github_workflow after prepare-job completes, so a prepare-time copy is empty. It has to happen at step time.

Fix

Provision /github/{home,workflow,file_commands} from the freshly merged /__w/_temp inside runScriptStep, in the same execPodStep that performs the temp merge — i.e. right before the step entrypoint runs. By then _work/_temp/_github_workflow/event.json is present, so the action sees the correct payload. It re-syncs each step, so later-arriving context files stay current. This restores the #287 behaviour within the new merge strategy from #293.

Testing

• npm run build-all (ncc bundle builds cleanly).
• Deployed on self-hosted kubernetes-novolume runners: verified live that job containers now have /github/workflow/event.json populated, and actions/dependency-review-action passes where it previously failed.

Happy to adjust placement (e.g. fold into writeRunScript) or add coverage if maintainers prefer.