docs: add DashScope API key to Docker prereqs, ffmpeg install guide, Phase 2 env vars

README.md

@@ -25,6 +25,7 @@ Backend → `http://localhost:8000` | Frontend → `http://localhost:5173`
 
 - Docker 24+ and Docker Compose v2
 - OpenRouter API key (or compatible LLM provider)
+- Alibaba Cloud DashScope API key (for video ASR transcription)
 
 ### Setup
 
@@ -184,6 +185,11 @@ docker run -d --name legco_test -p 8888:8000 \
   -e PROMPTS_DB_PATH=./data/prompts.db \
   -e HISTORY_DB_PATH=./data/history.db \
   -e CORS_ORIGINS='["http://localhost:5173","http://localhost:3000"]' \
+  -e DASHSCOPE_API_KEY=your_dashscope_key \
+  -e ASR_MODEL_NAME=qwen3-asr-flash \
+  -e ASR_REALTIME_MODEL_NAME=qwen3-asr-flash-realtime \
+  -e VIDEO_UPLOAD_DIR=./uploads \
+  -e MAX_VIDEO_SIZE_MB=300 \
   -v ~/woody/legco/data/chroma_db:/app/chroma_db \
   -v ~/woody/legco/data/document_chunk:/app/document_chunk \
   -v ~/woody/legco/data/data:/app/data \
@@ -235,6 +241,22 @@ Video → Audio → DashScope ASR → Transcript → QueryInput → RAG Pipeline
 **Requirements:**
 - `DASHSCOPE_API_KEY` in `.env`
 - `ffmpeg` on server (for batch transcription)
+- `dashscope` Python package (in `requirements.txt`)
+
+### Installing ffmpeg
+
+```bash
+# Ubuntu/Debian
+sudo apt install ffmpeg
+
+# macOS
+brew install ffmpeg
+
+# Static build (no root, any Linux)
+mkdir -p ~/.local/bin
+wget -qO- https://johnvansickle.com/ffmpeg/releases/ffmpeg-release-amd64-static.tar.xz | tar -xJ -C /tmp
+cp /tmp/ffmpeg-*-static/ffmpeg ~/.local/bin/
+```
 
 ## Notes