feat(uconsole): add cm5 cross-compiled nixosConfiguration

- New host: uconsole-cm5 (aarch64-linux, cross-built from x86_64)
- SSH authorizedKeys: gortium.main + ai-worker.main
- NetworkManager enabled (WiFi password via agenix later)
- Display: vc4/panel_cwu50/rp1_dsi with empty initrd
- Config.txt [pi5] section (not [cm5])
- Backlight fix service
- nixos-raspberrypi → gortium/cm5-cross-v1 fork (PR #197)
- nixpkgs-uconsole pinned to nixos-25.11 (kernel patch compat)

V3 branch saved as archive/uconsole-cm5-v3 (Reticulum/SDR/HAM config).

hosts/uconsole-cm5/configuration.nix

@@ -0,0 +1,112 @@
+{ config, lib, pkgs, keys, ... }:
+
+{
+  # Basic Host Info
+  networking.hostName = "uConsole";
+  time.timeZone = "America/Montreal";
+  i18n.defaultLocale = "en_CA.UTF-8";
+  system.stateVersion = "25.11";
+
+  # ============================================================
+  # SSH Access — ta clé + clé de déploiement
+  # ============================================================
+  services.openssh = {
+    enable = true;
+    settings.PermitRootLogin = "prohibit-password";
+    settings.PasswordAuthentication = false;
+  };
+
+  users.users.root = {
+    openssh.authorizedKeys.keys = [
+      keys.users.gortium.main
+      keys.users.ai-worker.main
+    ];
+  };
+
+  # ============================================================
+  # Networking — WiFi via NetworkManager
+  # ============================================================
+  networking.networkmanager.enable = true;
+
+  # WiFi connection — Thierry ajoutera le password dans un secret agenix
+  # networking.networkmanager.connections = { ... };
+
+  # ============================================================
+  # Kernel parameters from nixos-uconsole CM5 module
+  # ============================================================
+  boot.kernelParams = [
+    "8250.nr_uarts=1"
+    "console=tty1"
+  ];
+
+  # ============================================================
+  # Console font for 5" 720x1280 display
+  # ============================================================
+  console = {
+    earlySetup = true;
+    font = "ter-v24n";
+    packages = with pkgs; [ terminus_font ];
+  };
+
+  # ============================================================
+  # Display — vc4/panel_cwu50 loaded AFTER RP1 PCIe init
+  # Rien dans initrd — tout RP1 est derrière PCIe
+  # ============================================================
+  hardware.graphics.enable = true;
+
+  boot.kernelModules = [
+    "panel_cwu50"     # uConsole DSI panel driver
+    "vc4"             # VideoCore 4 KMS GPU driver
+    "rp1_dsi"         # RP1 DSI bridge driver
+  ];
+
+  boot.initrd.kernelModules = lib.mkForce [ ];
+
+  # ============================================================
+  # CM5 Config.txt — [pi5] section (pas [cm5])
+  # ============================================================
+  hardware.raspberry-pi.extra-config = ''
+    [all]
+    gpio=10=ip,np
+    gpio=11=op,dh
+
+    [pi5]
+    dtparam=pciex1=off
+    dtoverlay=clockworkpi-uconsole-cm5
+    dtoverlay=dwc2,dr_mode=host
+    dtoverlay=vc4-kms-v3d-pi5,cma-384
+    dtparam=nohdmi1=off
+  '';
+
+  # ============================================================
+  # CM5 Display Backlight Fix
+  # ============================================================
+  systemd.services.cm5-backlight-fix = {
+    description = "CM5 Display Backlight Fix";
+    after = [ "multi-user.target" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = let
+        fixScript = pkgs.writeShellScript "backlight-fix" ''
+          for bl in /sys/class/backlight/*/brightness; do
+            if [ -f "$bl" ]; then
+              max=$(cat "$(dirname "$bl")/max_brightness" 2>/dev/null || echo 100)
+              echo "$max" > "$bl" 2>/dev/null || true
+            fi
+          done
+        '';
+      in "${fixScript}";
+    };
+  };
+
+  # ============================================================
+  # Minimal packages
+  # ============================================================
+  environment.systemPackages = with pkgs; [
+    git
+    vim
+    htop
+    libgpiod      # GPIO control
+  ];
+}