chore(workflows): run doc freshness check every 4 hours and create PRs

[Copilot]

Summary

Updated the docs checker GitHub Agentic Workflow to run on a multi-hour cadence and remediate drift via pull requests instead of issues. This aligns the workflow output with code-change workflows rather than issue triage.

• Schedule cadence

  • Changed trigger from weekday-daily to every 4 hours.

• Safe output behavior

  • Switched front matter safe output from create-issue to create-pull-request (max: 1).

• Prompt contract

  • Rewrote task instructions/decision criteria/output format to direct the agent to open PRs (not issues) when drift is detected.

• Compiled workflow artifacts

  • Regenerated doc-freshness-check.lock.yml (and action lock metadata) to reflect the updated workflow contract.

on:
  schedule: every 4 hours
safe-outputs:
  create-pull-request:
    max: 1

Test plan

N/A — workflow behavior change is defined by front matter/prompt contract and reflected in regenerated lock artifacts.