Add sync.sh for content sync between local and server

- pull: server → local
- push: local → server
- watch: auto-push on file changes via fswatch
- status: dry-run diff
- dev.sh: ./dev.sh --sync pulls before starting

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dev.sh

@@ -12,6 +12,12 @@ cleanup() {
 }
 trap cleanup EXIT INT TERM
 
+# Optional: sync content from server
+if [ "${SYNC:-}" = "1" ] || [ "${1:-}" = "--sync" ]; then
+  echo "Syncing content from server..."
+  ./sync.sh pull
+fi
+
 # Start API in background
 echo "Starting RustyCMS API on http://127.0.0.1:3000 ..."
 cargo run &