Initial implementation: Bordanlage boat onboard system

Complete multiroom audio + navigation dashboard:
- Docker stack: SignalK, Snapcast (4 zones), librespot, shairport-sync, Mopidy, Jellyfin, Portainer
- React 18 + Vite dashboard with nautical dark theme
- Full mock system (SignalK NMEA simulation, Snapcast zones, Mopidy player)
- Real API clients for all services with reconnect logic
- SVG instruments: Compass, WindRose, Gauge, DepthSounder, SpeedLog
- Pages: Overview, Navigation, Audio (zones/radio/library), Systems
- Dev mode runs fully without hardware (make dev)

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

bordanlage/config/shairport.conf

@@ -0,0 +1,15 @@
+general = {
+  name = "Bordanlage AirPlay";
+  port = 5000;
+  interpolation = "auto";
+  output_backend = "pipe";
+};
+
+pipe = {
+  name = "/tmp/audio/airplay.pcm";
+};
+
+metadata = {
+  enabled = yes;
+  include_cover_art = yes;
+};