Update gstack skills to 1.58.5.0

[charlieviettq]

Summary

• Refreshes vendored gstack skills from garrytan/gstack main.
• Upstream version: 1.58.5.0.
• Upstream commit: 11de390be1be6849eb9a15f91ff4922dd16c589a.
• Adds refresh metadata at registry/gstack-sync.json and importer script at scripts/refresh-gstack-pack.py.
• Adds weekly/manual sync workflow that opens a review PR instead of auto-merging.
• Regenerates Claude parity artifacts and registry.

New mapped skills

• gstack/utility/diagram
• gstack/deploy-ship/document-generate
• gstack/ios/ios-clean
• gstack/ios/ios-design-review
• gstack/ios/ios-fix
• gstack/ios/ios-qa
• gstack/ios/ios-sync
• gstack/utility/make-pdf
• gstack/plan-review/spec

Validation

• python3 scripts/refresh-gstack-pack.py --dry-run
• python3 scripts/convert-to-claude.py --in-repo --force --write-map --prune-orphans
• python3 scripts/generate-registry.py
• python3 scripts/validate-skills.py --parity
• python3 scripts/generate-registry.py --check
• python3 scripts/skillhub.py eval-recommend

Notes

• This keeps gstack as a vendored skill pack, not a submodule/subtree.
• Top-level upstream toolchain/bin/extension/package files are not imported.
• Skill-local support assets referenced by the skills are imported where needed.