chore: add Claude Project Knowledge sync tooling

- scripts/sync-claude-docs.sh with sync/check/list/help subcommands
- scripts/install-claude-sync-hooks.sh for one-time hook setup
- .githooks/post-commit auto-syncs on dev-doc changes
- .githooks/pre-push warns (non-blocking) on stale sync
- .claude-sync.conf lists 11 synced documents
- SYNC_MANIFEST.md provides drift-detection anchor for Claude Chat
- package.json: npm run sync:docs | sync:check
- .gitignore excludes .claude-sync/ output directory

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude-sync.conf

@@ -0,0 +1,11 @@
+CLAUDE.md
+.cursorrules
+dev-docs/SCHEMA.md
+dev-docs/API.md
+dev-docs/ARCH-FORM-BUILDER.md
+dev-docs/AUTH_ARCHITECTURE.md
+dev-docs/VUEXY_COMPONENTS.md
+dev-docs/BACKLOG.md
+dev-docs/SECURITY_AUDIT.md
+dev-docs/design-document.md
+dev-docs/UX_SPEC_FESTIVAL_HIERARCHY.md