feat(14900k): add MediaTek MT7927 WiFi and Bluetooth support

Add a private module to enable MediaTek MT7927 (Filogic 380) support.
This includes a firmware path fix for Bluetooth and a systemd service
to force-load patched out-of-tree kernel modules, bypassing in-tree
drivers that lack support for this hardware on nixos-unstable.

modules/hosts/14900k/configuration.nix

@@ -23,6 +23,7 @@
         ./_private/streaming-display.nix
         ./_private/ai.nix
         ./_private/media-disk.nix
+        ./_private/mediatek-mt7927.nix
         ./_private/jellyfin-nfs-export.nix
         ./_private/moonfin-flatpak.nix
       ];
@@ -44,7 +45,6 @@
           libvdpau-va-gl
         ];
       };
-
       environment.sessionVariables = {
         LIBVA_DRIVER_NAME = "iHD";
         # Force VA-API to use the Intel iGPU render node (otherwise libva may pick NVIDIA and iHD fails).