Initial commit: overlay + sender pages for StreamLabs browser source

Express + Socket.IO backend with Google login on the sender page,
a transparent overlay page for OBS/StreamLabs Browser Source, and
TTS voice-over via the edge-tts Python CLI (same engine as
t2sTelegramBot). Dockerized for deployment.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,10 @@
+services:
+  app:
+    build: .
+    ports:
+      - "3000:3000"
+    environment:
+      - PORT=3000
+      - GOOGLE_CLIENT_ID=${GOOGLE_CLIENT_ID}
+      - SESSION_SECRET=${SESSION_SECRET}
+    restart: unless-stopped