refactor: migrate from Codeberg to Gitea and rename rhemawave to radiantwave

- Update all Codeberg URLs to gitea.radiantwavetech.com/RadiantWaveTech/
- Rename flake inputs: rhemawave → radiantwave, rhemawave-dev → radiantwave-dev
- Rename NixOS configs: rhemawavekiosk* → radiantwavekiosk*
- Update systemd services, data paths, and binary references
- Rename plymouth theme files
- Update CI workflow, documentation, and build scripts

rotated_display.nix

@@ -1,10 +1,10 @@
-{ pkgs, rhemawave, ...}:
+{ pkgs, radiantwave, ...}:
 let
-  rhemaApp = rhemawave.packages.${pkgs.system}.default;
+  radiantApp = radiantwave.packages.${pkgs.system}.default;
   kioskscript = pkgs.writeShellScript "kiosk-start" ''
     OUTPUT=$(${pkgs.wlr-randr}/bin/wlr-randr | grep -m1 '^\S' | awk '{print $1}')
     ${pkgs.wlr-randr}/bin/wlr-randr --output "$OUTPUT" --transform 90
-    exec ${rhemaApp}/bin/rhemawave -d -s
+    exec ${radiantApp}/bin/radiantwave -d -s
   '';
 in
 {
@@ -27,7 +27,7 @@ in
       export WLR_RENDERER=pixman
       export WLR_NO_HARDWARE_CURSORS=1
 
-      mkdir -p /home/kiosk/.local/share/rhemawave
+      mkdir -p /home/kiosk/.local/share/radiantwave
       exec dbus-run-session cage -- ${kioskscript} > /tmp/kiosk.log 2>&1
     fi
   '';