feat: enhance discovery, vibe sessions, and library enrichment

workers/Dockerfile

@@ -1,5 +1,10 @@
 FROM node:20-slim
-RUN apt-get update && apt-get install -y ffmpeg && rm -rf /var/lib/apt/lists/*
+# yt-dlp is intentionally opt-in. Enabling its image build alone does not make
+# acquisition live: the worker additionally requires explicit runtime gates.
+ARG INSTALL_YTDLP=false
+RUN apt-get update && apt-get install -y ffmpeg \
+    && if [ "$INSTALL_YTDLP" = "true" ]; then apt-get install -y yt-dlp; fi \
+    && rm -rf /var/lib/apt/lists/*
 WORKDIR /app
 COPY package*.json ./
 RUN npm install --legacy-peer-deps