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.

bot/src/bridge.ts

@@ -0,0 +1,52 @@
+/**
+ * HTTP client for the Python brain bridge (bridge/server.py).
+ * All AI work (STT, reply engine, TTS) lives behind these calls.
+ */
+import { config } from "./config.ts";
+
+export interface ConverseResult {
+  transcript: string;
+  language?: string | null;
+  reply: string;
+  error?: string | null;
+  /** base64-encoded 16-bit PCM WAV of the spoken reply, or null if TTS off */
+  audio_b64?: string | null;
+}
+
+export interface TextResult {
+  reply: string;
+  error?: string | null;
+  audio_b64?: string | null;
+}
+
+/** Full voice turn: WAV in -> {transcript, reply, reply audio}. */
+export async function converse(wav: Buffer): Promise<ConverseResult> {
+  const res = await fetch(`${config.bridgeUrl}/converse`, {
+    method: "POST",
+    headers: { "content-type": "audio/wav" },
+    body: wav,
+  });
+  if (!res.ok) throw new Error(`bridge /converse ${res.status}: ${await res.text()}`);
+  return (await res.json()) as ConverseResult;
+}
+
+/** Text-only turn (used by /자비스 ask). */
+export async function ask(text: string): Promise<TextResult> {
+  const res = await fetch(`${config.bridgeUrl}/text`, {
+    method: "POST",
+    headers: { "content-type": "application/json" },
+    body: JSON.stringify({ text }),
+  });
+  if (!res.ok) throw new Error(`bridge /text ${res.status}: ${await res.text()}`);
+  return (await res.json()) as TextResult;
+}
+
+export async function health(): Promise<any> {
+  const res = await fetch(`${config.bridgeUrl}/health`);
+  return res.json();
+}
+
+export function decodeWav(audio_b64?: string | null): Buffer | null {
+  if (!audio_b64) return null;
+  return Buffer.from(audio_b64, "base64");
+}