Add kiosk desktop app

Tauri app for the Pi. Media runs through the native LiveKit SDK because
WebKitGTK has no WebRTC, with frames encoded in Rust and drawn to a canvas
under the annotation overlay.

Claude-Session: https://claude.ai/code/session_01SS9F92jb51bMCRCKem6QtD

apps/kiosk-client/src-tauri/.gitignore

@@ -0,0 +1,7 @@
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+
+# Generated by Tauri
+# will have schema files for capabilities auto-completion
+/gen/schemas