[CHORE] Align sync-main-to-dev checkout action pin with repository standard

[c-vigo]

Chore Type

CI / Build change

Description

The sync-main-to-dev workflow currently pins actions/checkout to 34e114876b0b11c390a56381ad16ebd13914f8d5 # v4 in two steps, while the repository standard in other workflows is de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2.

Align both checkout steps to the repository-standard pinned SHA to keep workflow behavior and supply-chain posture consistent.

Acceptance Criteria

• Update both actions/checkout entries in .github/workflows/sync-main-to-dev.yml to the repository-standard pin (de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2)
• Ensure mirrored/generated workflow assets remain consistent where applicable
• CI/workflow lint checks pass after the update

Implementation Notes

• Target file: .github/workflows/sync-main-to-dev.yml
• Context: Copilot review on vig-os/devcontainer-smoke-test#27 identified the mismatch.
• Keep scope limited to pin alignment only (no behavioral refactors).

Related Issues

Related to #169

Priority

Medium

Changelog Category

Changed

Additional Context

Follow-up from review feedback on:
vig-os/devcontainer-smoke-test#27