feat(uConsole): add disko, backlight fix, GPIO 23, mt7921u

- Add disko flake input + partition config (/boot/firmware, /, /home)
- Add cm5-backlight-fix service as display fallback
- Add enable-gpio23-usb-hub service for internal USB hub
- Add mt7921u kernel module for MediaTek AC1200 WiFi
- Add gpiod package for GPIO userspace control

hosts/uConsole/configuration.nix

@@ -1,5 +1,19 @@
 { config, lib, pkgs, paths, self, keys, ... }:
 
+let
+  # Backlight fallback for CM5 display quirk
+  # The kernel driver usually handles this, but some boots need a kick
+  backlightFixScript = pkgs.writeShellScript "backlight-fix" ''
+    # Try sysfs backlight control
+    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
+
 {
   # Basic Host Info
   networking.hostName = "uConsole";
@@ -56,6 +70,7 @@
     htop
     tmux
     neovim
+    gpiod                       # GPIO control (for internal USB hub, AIO modules)
 
     # ===== HAM Radio =====
     js8call
@@ -139,9 +154,10 @@
   };
 
   # ============================================================
-  # Kernel modules for SDR and radio
+  # Kernel modules for SDR, radio, and WiFi
   # ============================================================
   boot.kernelModules = [
+    "mt7921u"         # MediaTek MT7921 USB WiFi (uConsole AC1200)
     "88x2bu"          # Realtek 8812/8821BU USB WiFi (common adapter)
     "rtl8xxxu"        # RTL8188/8192/8723 USB WiFi
     "rtl2832_sdr"     # RTL-SDR kernel module
@@ -168,4 +184,37 @@
   # Reticulum uses its own encryption and doesn't need open ports
   # for basic mesh operations (peer-to-peer discovery).
   # For TCP interfaces, open additional ports as needed.
+
+  # ============================================================
+  # CM5 Display Backlight Fix
+  # The kernel driver initializes backlight, but some boots fail.
+  # This service kicks it after boot as a reliable fallback.
+  # ============================================================
+  systemd.services.cm5-backlight-fix = {
+    description = "CM5 Display Backlight Fix";
+    after = [ "multi-user.target" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      ExecStart = "${backlightFixScript}";
+    };
+  };
+
+  # ============================================================
+  # Internal USB Hub Enable (GPIO 23)
+  # The Hacker Gadgets AIO V2 board has an internal USB hub for
+  # the AC1200 WiFi, SDR, and other peripherals. GPIO 23 must be
+  # HIGH to power the hub. CM5 defaults GPIO 23 to LOW.
+  # ============================================================
+  systemd.services.enable-gpio23-usb-hub = {
+    description = "Enable Internal USB Hub (GPIO 23)";
+    before = [ "network.target" ];
+    wantedBy = [ "multi-user.target" ];
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+      ExecStart = "${pkgs.gpiod}/bin/gpioset 0 23=1";
+      ExecStop = "${pkgs.gpiod}/bin/gpioset 0 23=0";
+    };
+  };
 }