[CI/Automation] Add weekly cron job for automated code review workflow

[Al629176]

Create a weekly scheduled cron job to run an automated code review workflow.

Scope:

• Add GitHub Actions schedule (weekly)
• Define target branch scope (default main)
• Run static checks/review script
• Post summary output (issue/comment/artifact)
• Notify owners on findings

Tasks:

• Implement workflow YAML with schedule
• Add review script entrypoint
• Configure permissions/secrets
• Add output/report format
• Add failure handling and retries
• Document runbook and disable/override controls

Acceptance:

• Workflow runs weekly without manual trigger
• Produces actionable review report
• Alerts maintainers when issues are detected.