fixes and docs

docs/systems/matt-nixos.md

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+# Desktop (matt-nixos)
+
+`systems/x86_64-linux/matt-nixos/`
+
+## Hardware
+
+- **CPU**: AMD
+- **GPU**: AMD (LACT for fan/power control, OpenRGB)
+- **Disk**: NVMe with LUKS encryption (disko)
+- **Security**: TPM2, Lanzaboote (Secure Boot)
+
+## Key Features
+
+- GNOME as the primary desktop (Hyprland available but disabled)
+- COSMIC available as a specialisation (`nixos-rebuild switch --specialisation cosmic`)
+- Gaming — Steam, Gamemode, Gamescope, Lossless Scaling (`lsfg-vk`)
+- AMD GPU management via LACT
+- CoolerControl for fan curves
+- Impermanence (ephemeral root)
+- iwd as the Wi-Fi backend
+- VSCodium as `$EDITOR`/`$VISUAL`
+
+## Desktop Specialisations
+
+| Specialisation | Description |
+|---|---|
+| *(default)* | GNOME |
+| `cosmic` | COSMIC DE (enables `mjallen.desktop.cosmic`, disables GNOME/Hyprland) |
+
+## Network
+
+- **Hostname**: matt-nixos
+- **Wi-Fi backend**: iwd (via NetworkManager)
+
+## Configuration Files
+
+| File | Purpose |
+|---|---|
+| `default.nix` | Main config |
+| `boot.nix` | Lanzaboote, kernel |
+| `filesystems.nix` | Disk layout |
+| `sops.nix` | Secret declarations |
+| `wifi-fixer.nix` | NetworkManager Wi-Fi workaround |
+| `services/lsfg-vk/` | Lossless Scaling frame generation |
+| `services/ratbagd/` | Gaming mouse config (libratbag) |
+| `services/restic/` | Restic backup jobs |
+
+## Secrets
+
+Secrets are in `secrets/desktop-secrets.yaml`, encrypted for: `matt`, `desktop`, `admin`, `jallen-nas`.