feat: update DEF CON 34 firmware to 2.8.0.c800fc8

Points the DEF CON 34 edition at the build that restores the custom boot logo
on MUI hardware (device-ui pin held at ef573c3) and carries the signing/ingress
hardening from firmware #11282. Was 2.8.0.8adc7c3.

version / id / title / zipUrl bumped; slug and release notes unchanged.

Author: thebentern

data/eventFirmware.json

@@ -123,10 +123,10 @@
       },
       "firmware": {
         "slug": "defcon34",
-        "version": "2.8.0.8adc7c3",
-        "id": "v2.8.0.8adc7c3",
-        "title": "Meshtastic Firmware 2.8.0.8adc7c3",
-        "zipUrl": "https://github.com/meshtastic/meshtastic.github.io/raw/master/event/defcon34/firmware-2.8.0.8adc7c3.zip",
+        "version": "2.8.0.c800fc8",
+        "id": "v2.8.0.c800fc8",
+        "title": "Meshtastic Firmware 2.8.0.c800fc8",
+        "zipUrl": "https://github.com/meshtastic/meshtastic.github.io/raw/master/event/defcon34/firmware-2.8.0.c800fc8.zip",
         "releaseNotes": "## Welcome to DEF CON 34! 💀\n\nThis firmware has been customized for DEF CON 34 with factory default configurations.\n\n### ⚠️ Important: Backup Before Flashing\n\nIf your device has existing settings or encryption keys, **backup your keys / configurations** before proceeding. Flashing will reset your device to factory settings for the event.\n\n### Quick Start\n\n1. Ensure a **data-capable USB cable** is connected\n2. Select your device type\n3. Choose \"Full Erase and Install\"\n4. After flashing, download the Meshtastic app and pair via Bluetooth\n5. If you updated from a previous version or installed a UF2 on an NRF52 device, you will need to perform a factory reset on the device to activate the DEF CON mode.\n\n**Happy meshing from Las Vegas!**"
       }
     },