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>

.gitignore

@@ -54,3 +54,6 @@ docs/.vitepress/cache
 # Local deploy wrapper (per-developer SSH alias)
 /run-deploy-from-local.sh
 !/run-deploy-from-local.example.sh
+
+# Claude Project Knowledge sync output (regenerated by scripts/sync-claude-docs.sh)
+.claude-sync/