feat: 1080p60 NVENC selfbot broadcast (8 Mbps default)

Bump the default broadcast to 1080p 60fps at 8 Mbps and route both encode
stages through the GPU (RTX 5050, h264_nvenc) so 60fps stays smooth without
loading the 4-core host.

- selfbot.ts: capture ffmpeg uses h264_nvenc when streamHw is on (falls back
  to software x264 otherwise), and prepareStream now passes Encoders.nvenc()
  so the library's transcode runs on the GPU too. Guard loadLib for Encoders.
- config.ts: VNC_FRAMERATE default 30 -> 60, VNC_BITRATE_KBPS 4000 -> 8000.
- .env.example: document the new 1080p60/8 Mbps defaults and STREAM_HW.

Verified locally: h264_nvenc x11grab holds a steady 60fps with headroom,
Encoders.nvenc() returns valid h264_nvenc settings, and tsc --noEmit passes.
Live Discord voice-channel verification pending a host reboot.

.env.example

@@ -58,13 +58,18 @@ STREAM_BACKEND=selfbot
 # The VNC desktop runs on X display :1 (see docs/vnc-xfce-setup.md)
 VNC_DISPLAY=:1
 VNC_RESOLUTION=1920x1080
-VNC_FRAMERATE=30
-VNC_BITRATE_KBPS=4000
+# 1080p60 broadcast. 8 Mbps suits 60fps (YouTube-style 1080p60 sits ~8-12 Mbps);
+# drop to 30/4000 for a lighter stream. Max bitrate is 1.5x this value.
+VNC_FRAMERATE=60
+VNC_BITRATE_KBPS=8000
 
 # --- selfbot backend ---
 # A THROWAWAY/burner Discord user account token. NEVER your main account.
 # Using a selfbot violates Discord ToS and can get the account banned.
 DISCORD_SELFBOT_TOKEN=
+# Hardware (NVENC) encode for the stream. 1 = use the GPU (recommended for
+# 1080p60), 0 = software x264. Requires an NVIDIA GPU + ffmpeg built with nvenc.
+STREAM_HW=1
 
 # --- novnc backend ---
 # e.g. http://192.168.10.9:6080/vnc.html  (websockify --web=/usr/share/novnc 6080 localhost:5901)