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/stream/selfbot.ts

@@ -0,0 +1,116 @@
+/**
+ * Selfbot live-stream backend (default).
+ *
+ * Streams the VNC X display (:1) into the voice channel as a real Discord
+ * "Go Live" broadcast. Discord blocks video from *bot* accounts, so this path
+ * requires a USER account token (a "selfbot"), which violates Discord ToS and
+ * can get the account banned. Use a throwaway/burner account, never your main.
+ *
+ * Dependencies are optional (native): install with
+ *   bun add discord.js-selfbot-v13 @dank074/discord-video-stream
+ * They are dynamically imported so the core bot installs/runs without them.
+ *
+ * Library API targets @dank074/discord-video-stream v6 (Streamer / prepareStream
+ * / playStream). If a different major is installed, the import guard below will
+ * point you at the docs rather than crash cryptically.
+ */
+import type { AppConfig } from "../config.ts";
+import type { ScreenStreamer, StreamContext } from "./index.ts";
+
+export class SelfbotStreamer implements ScreenStreamer {
+  readonly kind = "selfbot" as const;
+  private config: AppConfig;
+  private streamer: any = null;
+  private controller: AbortController | null = null;
+  private active = false;
+
+  constructor(config: AppConfig) {
+    this.config = config;
+  }
+
+  isActive() {
+    return this.active;
+  }
+
+  private async loadLib() {
+    let selfbot: any, videoStream: any;
+    try {
+      selfbot = await import("discord.js-selfbot-v13");
+      // Optional native dep; resolved at runtime only. Version/name can vary by
+      // upstream release, so we don't hard-bind its types at compile time.
+      // @ts-ignore - optional dependency, may be absent until `bun add`ed
+      videoStream = await import("@dank074/discord-video-stream");
+    } catch (e) {
+      throw new Error(
+        "셀프봇 송출 의존성이 없습니다. 설치: bun add discord.js-selfbot-v13 @dank074/discord-video-stream\n" +
+          `원본 오류: ${(e as Error).message}`,
+      );
+    }
+    if (!videoStream.Streamer || !videoStream.prepareStream || !videoStream.playStream) {
+      throw new Error(
+        "@dank074/discord-video-stream v6 API(Streamer/prepareStream/playStream)를 찾지 못했습니다. " +
+          "package.json 버전을 ^4.2.1(=v6 npm 태그)로 맞추거나 docs를 확인하세요.",
+      );
+    }
+    return { selfbot, videoStream };
+  }
+
+  async start(ctx: StreamContext): Promise<string> {
+    if (this.active) return "이미 송출 중입니다.";
+    if (!this.config.selfbotToken) {
+      return "DISCORD_SELFBOT_TOKEN이 설정되지 않았습니다 (.env). 버너 계정 토큰을 넣어주세요.";
+    }
+    const { selfbot, videoStream } = await this.loadLib();
+    const { Streamer, prepareStream, playStream, Utils } = videoStream;
+
+    this.streamer = new Streamer(new selfbot.Client());
+    await this.streamer.client.login(this.config.selfbotToken);
+    await this.streamer.joinVoice(ctx.guildId, ctx.voiceChannelId);
+
+    // Grab the VNC X display with ffmpeg's x11grab and let the library
+    // encode/transport it. NVENC (RTX 5050) is used if available.
+    const input = `x11grab:${this.config.vncDisplay}`;
+    const { command, output } = prepareStream(
+      input,
+      {
+        width: parseInt(this.config.vncResolution.split("x")[0] ?? "1920", 10),
+        height: parseInt(this.config.vncResolution.split("x")[1] ?? "1080", 10),
+        frameRate: this.config.vncFramerate,
+        bitrateVideo: this.config.vncBitrateKbps,
+        videoCodec: Utils?.normalizeVideoCodec ? Utils.normalizeVideoCodec("H264") : "H264",
+        // x11grab needs to be set as the input format for ffmpeg
+        customHeaders: undefined,
+        inputFormat: "x11grab",
+        inputSize: this.config.vncResolution,
+      },
+      (this.controller = new AbortController()).signal,
+    );
+
+    command.on("error", (err: Error) => {
+      if (!this.controller?.signal.aborted) console.error("[selfbot] ffmpeg error:", err);
+    });
+
+    this.active = true;
+    // Fire-and-forget; resolves when the stream ends.
+    playStream(output, this.streamer, { type: "go-live" })
+      .catch((err: Error) => console.error("[selfbot] playStream:", err))
+      .finally(() => {
+        this.active = false;
+      });
+
+    return "🔴 셀프봇으로 VNC 화면을 음성채널에 실시간 송출 중입니다 (Go Live).";
+  }
+
+  async stop(): Promise<void> {
+    this.controller?.abort();
+    this.controller = null;
+    try {
+      this.streamer?.leaveVoice?.();
+      this.streamer?.client?.destroy?.();
+    } catch {
+      /* ignore */
+    }
+    this.streamer = null;
+    this.active = false;
+  }
+}