add: Docker image and compose for containerized deploy

Multi-stage build (cgo for the SQLite logger) on debian-slim with ffmpeg,
opus-tools, and ca-certificates bundled. Compose mounts ./data/config.yaml
and ./data/media; SIGTERM cancels in-flight encodes cleanly.

docker-compose.yml

@@ -0,0 +1,10 @@
+services:
+  videnc:
+    build: .
+    container_name: videnc-vibe
+    restart: unless-stopped
+    volumes:
+      - ./data/config.yaml:/config/config.yaml:ro # your config — paths inside must point at /data/*
+      - ./data/media:/data # holds input/ output/ originals/ failed/ work/ + logs
+    # Uncomment to delete originals after a successful encode (appends -d to the entrypoint):
+    # command: ["-d"]