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

commands.md

@@ -2,11 +2,11 @@ Build ISO installer
 nix build .#nixosConfigurations.installer-iso.config.system.build.isoImage
 
 Build kiosk system and push to Attic cache
-nix build .#nixosConfigurations.rhemawavekiosk.config.system.build.toplevel
+nix build .#nixosConfigurations.radiantwavekiosk.config.system.build.toplevel
 attic push kiosk ./result
 
 Deploy to a specific kiosk over SSH
-nixos-rebuild switch --flake .#rhemawavekiosk --target-host root@<host>
+nixos-rebuild switch --flake .#radiantwavekiosk --target-host root@<host>
 
 ---
 
@@ -16,7 +16,7 @@ The build commands follow the flake output attribute tree. Start with `flake.nix
 
 ```nix
 nixosConfigurations = {
-  rhemawavekiosk = nixpkgs.lib.nixosSystem { ... };   # production machine
+  radiantwavekiosk = nixpkgs.lib.nixosSystem { ... };   # production machine
   installer-iso  = nixpkgs.lib.nixosSystem { ... };   # USB installer
 };
 ```
@@ -31,7 +31,7 @@ by walking the attribute tree with dots:
 │ │                    │                            toplevel  = full system closure
 │ │                    │                            isoImage  = bootable ISO
 │ │                    │
-│ │                    └─ name from flake.nix (rhemawavekiosk, installer-iso)
+│ │                    └─ name from flake.nix (radiantwavekiosk, installer-iso)
 │ │
 │ └─ nixosConfigurations = standard flake output for NixOS systems
 │
@@ -40,4 +40,4 @@ by walking the attribute tree with dots:
 
 You can explore what's available with:
   nix eval .#nixosConfigurations --apply builtins.attrNames
-  nix eval .#nixosConfigurations.rhemawavekiosk.config.system.build --apply builtins.attrNames
+  nix eval .#nixosConfigurations.radiantwavekiosk.config.system.build --apply builtins.attrNames