feat: vendor Discord video stream workspace

Add Discord-video-stream as a vendored workspace dependency and wire it to use the local selfbot package for development.

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

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "vendor/discord.js-selfbot-v13"]
 	path = vendor/discord.js-selfbot-v13
 	url = ssh://git@43.134.105.109:22222/exceed/discord.js-selfbot.git
+[submodule "vendor/Discord-video-stream"]
+	path = vendor/Discord-video-stream
+	url = ssh://git@43.134.105.109:22222/exceed/Discord-video-stream.git