Add sync-skills automation + .gitignore whitelist + update local skills

Update obsidian-study-vault-builder for Obsidian 1.12.7 CLI binary

feat: project-retrospective v3 — context-aware default, prior retro reuse

feat: deep-brainstorming skill v2 (#5)

fix: add model fallback guidance for non-opus users

fix: remove last two project-specific references

fix: frame correction patterns as universal seeds, not exhaustive list

feat: optimize description + live-fire validated

fix: synthesizer input + deliverables in incremental template

feat: project-retrospective v2 — incremental mode + output path

Add project-retrospective to README

Add project-retrospective skill

fix(ci): add permissions to shared workflow callers

ci: add Claude Code shared workflows

Update pdf-guard README with accurate thresholds and RLM features