feat(branding): use Ulicraft goat logo in header, ServerCard, and server icon

- landing header + footer brand: swap the Creeper pixel-art for the
  ulicraft-logo-mini.svg goat mark.
- ServerCard fallback icon: same logo (real SLP favicon still overrides on
  a successful ping).
- minecraft: set ICON=/extras/server-icon.png + OVERRIDE_ICON so the
  in-game server-list entry and the SLP favicon use the goat logo. PNG
  ships in ./runtime (mounted /extras).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -67,6 +67,11 @@ services:
       DIFFICULTY: "normal"
       MODE: "survival"
       MOTD: "Uli LAN party"
+      # Server-list icon (auto-scaled to 64x64). PNG lives in ./runtime (mounted
+      # /extras); OVERRIDE_ICON re-applies it on every boot. Also surfaces in the
+      # landing ServerCard via the SLP favicon.
+      ICON: "/extras/server-icon.png"
+      OVERRIDE_ICON: "TRUE"
       MAX_PLAYERS: "10"
       VIEW_DISTANCE: "10"
       SIMULATION_DISTANCE: "8"