fix: re-enable wifi — scan only killed FPS on NixOS, not bare-metal
Bare-metal runs at 60fps and can absorb the iw scan overhead.
The FPS drop was NixOS-specific (slow DRM page flip compounded
with scan stalls). Restore full wifi_init + autoconnect.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>