[nix-deck] Use NixOS unstable for better Jovian compatibility

- Switch nix-deck to use nixpkgs-unstable and unstable home-manager/plasma-manager
- Remove jovian-compat.nix shim (not needed on unstable)
- Add bitwarden-desktop compatibility overlay for stable/unstable coexistence
- Update hardware-configuration.nix with actual Steam Deck hardware detection
- Add 8GB swap file configuration
- Configure AMD CPU microcode updates

This allows nix-deck to work with the latest Jovian-NixOS while keeping other
machines on stable 25.05.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

machines/nix-deck/hardware-configuration.nix

@@ -1,26 +1,35 @@
-# This is a placeholder hardware configuration for the Steam Deck.
-# Run `nixos-generate-config --show-hardware-config` on the actual device
-# to generate the real hardware configuration, then merge the jovian settings below.
+# Hardware configuration for Steam Deck (nix-deck)
+# Generated from nixos-generate-config on 2025-11-17
 
 { config, lib, pkgs, modulesPath, ... }:
 
 {
-  imports = [ ];
+  imports = [
+    (modulesPath + "/installer/scan/not-detected.nix")
+  ];
 
-  # Steam Deck specific hardware configuration
+  # Steam Deck specific hardware configuration (Jovian)
   jovian.devices.steamdeck = {
     enable = true;
     autoUpdate = false;  # Set to true if you want automatic firmware updates
   };
 
-  # TODO: Replace this with actual hardware configuration from the Steam Deck
-  # Run `nixos-generate-config --show-hardware-config` on the device and merge it here
-
-  # Minimal placeholder configuration to allow flake to build
-  boot.initrd.availableKernelModules = [ ];
+  # Kernel modules detected by nixos-generate-config
+  boot.initrd.availableKernelModules = [
+    "nvme"
+    "xhci_pci"
+    "usb_storage"
+    "uas"
+    "usbhid"
+    "sd_mod"
+    "sdhci_pci"
+  ];
   boot.initrd.kernelModules = [ ];
-  boot.kernelModules = [ ];
+  boot.kernelModules = [ "kvm-amd" ];
+  boot.extraModulePackages = [ ];
 
+  # IMPORTANT: Update these filesystem configurations based on your actual partition layout
+  # The configuration below is a placeholder - adjust according to how you partitioned the disk
   fileSystems."/" = {
     device = "/dev/disk/by-label/nixos";
     fsType = "ext4";
@@ -31,7 +40,12 @@
     fsType = "vfat";
   };
 
-  swapDevices = [ ];
+  swapDevices = [{
+    device = "/swapfile";
+    size = 8192;  # 8GB swap file
+  }];
 
+  # AMD CPU microcode updates
   nixpkgs.hostPlatform = lib.mkDefault "x86_64-linux";
+  hardware.cpu.amd.updateMicrocode = lib.mkDefault config.hardware.enableRedistributableFirmware;
 }