Add Discord-native hybrid front-end for Jarvis (bot + bridge)

Transform isair/jarvis into a Discord-controlled voice assistant running on
the Ubuntu VNC desktop, keeping the mature ~39k-line Python brain intact.

- bot/ (Node + bun, discord.js): /자비스 slash commands (ephemeral),
  voice channel join + voice receive/playback, pluggable VNC screen broadcast
  (selfbot live / noVNC / screenshot)
- bridge/ (Python, Flask): wraps jarvis STT + run_reply_engine + Piper TTS
  behind a thin localhost HTTP API
- .env.example, scripts/ (start_bridge/start_bot/dev), README rewrite,
  docs/language-comparison.md and docs/vnc-xfce-setup.md

Language decision: hybrid (Python brain + Node/bun Discord layer) because
Discord blocks bot video; native screen broadcast only works via a Node
selfbot library.

scripts/dev.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+# Run brain bridge + bot together for local development.
+# The bridge expects the VNC desktop on DISPLAY :1 for screen capture.
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+./scripts/start_bridge.sh &
+BRIDGE_PID=$!
+trap 'kill $BRIDGE_PID 2>/dev/null || true' EXIT
+
+# Give the bridge a moment to bind its port before the bot queries /health.
+sleep 2
+./scripts/start_bot.sh