feat(stream): STREAM_BROWSER flag + make toolbar-hide/subtitles broadcast-wide

- Add STREAM_BROWSER (.env) gating screen-share/browser mode. false => the
  /자비스 stream command stays voice + API/MCP only (no Go-Live); true (default)
  => screen share as before. (Browser-driven info retrieval in true mode is a
  follow-up build; the bot has no browser-control tools yet.)
- Make the two test-time fixes broadcast-wide defaults via broadcast-helper.mjs:
  it now also watches every tab for HTML5 fullscreen and toggles Chrome window
  fullscreen so the address bar is hidden for ANY video (xfwm4 won't hide it on
  'f' alone), restoring on exit. Subtitles were already enforced per video.
  scenario.mjs drops its own fullscreen toggle and relies on the helper.
- Revert the test-settings env vars from .env.example (not wanted).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

bot/src/config.ts

@@ -47,6 +47,10 @@ export const config = {
   // STREAM_AUDIO=0 to mute; STREAM_AUDIO_SOURCE overrides the capture source.
   streamAudio: opt("STREAM_AUDIO", "1") !== "0",
   streamAudioSource: opt("STREAM_AUDIO_SOURCE", "@DEFAULT_MONITOR@"),
+  // Screen-share + browser mode. true = the bot may go Live (Go-Live screen
+  // share of the VNC desktop) and drive the on-screen browser for real-time
+  // info. false = no screen share; use voice + API/MCP tools for info only.
+  screenBrowser: opt("STREAM_BROWSER", "true") !== "false",
 
   // novnc backend
   novncUrl: opt("NOVNC_URL", ""),

bot/src/index.ts

@@ -111,6 +111,11 @@ async function handleStream(i: ChatInputCommandInteraction) {
       }
     },
   };
+  if (!config.screenBrowser) {
+    return i.editReply(
+      "화면 공유(브라우저) 모드가 꺼져 있습니다 (STREAM_BROWSER=false). 음성 + API/MCP 모드로만 동작합니다.",
+    );
+  }
   if (config.streamBackend === "selfbot" && !ctx.voiceChannelId) {
     return i.editReply("셀프봇 송출은 음성 채널 안에서 호출해야 합니다. 음성 채널에 들어간 뒤 다시 시도하세요.");
   }