Enable CONFIG_MT7927E for MediaTek MT7927 (Filogic 380) WiFi 7 support

## Hardware

- **Card:** MediaTek MT7927 (Filogic 380) WiFi 7
- **PCI ID:** `14c3:7927`
- **lspci output:** `6f:00.0 Network controller: MEDIATEK Corp. MT7927 802.11be 320MHz 2x2 PCIe Wireless Network Adapter [Filogic 380]`
- **Kernels tested:** `7.1.6-1-cachyos`, `7.1.6-1-cachyos-deckify`, `6.18.42-1-cachyos-lts`
- **Board:** ASUS (AMD Ryzen 9 9850X3D)
- **Repo:** cachyos-znver4

## Problem

`CONFIG_MT7927E` is not enabled in any current CachyOS kernel build. The card is detected on PCI but no driver binds — no wireless interface appears.

The existing `mt7925e` driver (which is compiled in) does not cover PCI ID `14c3:7927`:
```
alias: pci:v000014C3d00007925sv*sd*bc*sc*i*
alias: pci:v000014C3d00000717sv*sd*bc*sc*i*
```

`lsmod | grep mt7` shows no loaded WiFi modules by default.

## Kernel Status

`CONFIG_MT7927E` was merged into Linux mainline in kernel 6.14. The driver lives at:
```
drivers/net/wireless/mediatek/mt76/mt7927/
```

## Firmware

WiFi firmware is available in linux-firmware git (not yet in the packaged version):
- `mediatek/mt7927/WIFI_MT6639_PATCH_MCU_2_1_hdr.bin`
- `mediatek/mt7927/WIFI_RAM_CODE_MT6639_2_1.bin`

Bluetooth firmware (`mediatek/mt7927/BT_RAM_CODE_MT6639_2_1_hdr.bin`) is not yet upstream — causes continuous dmesg spam at ~500ms intervals:
```
bluetooth hci0: Direct firmware load for mediatek/mt7927/BT_RAM_CODE_MT6639_2_1_hdr.bin failed with error -2
```

## Requested Change

Please enable `CONFIG_MT7927E=m` in the kernel config for `linux-cachyos`. LTS backport would be appreciated once upstream supports it.

## System Info
```
OS: CachyOS (znver4), fresh install August 2026
Kernel: 7.1.6-1-cachyos
CPU: AMD Ryzen 9 9850X3D
lspci: 6f:00.0 0280: 14c3:7927
```

Start with the linux-cachyos kernel configuration and compare the existing mt7925e setting with the requested CONFIG_MT7927E=m option. Inspect drivers/net/wireless/mediatek/mt76/mt7927/ and verify the resulting build exposes the module for PCI ID 14c3:7927. Done means the relevant kernel configuration enables the driver; the documented firmware and Bluetooth limitations should remain explicit.

Written by the indexing model from the issue text.