fix: resolve websockets version conflict and use CPU-only torch

- Upgrade websockets from ==12.0 to >=13.0 (openai[realtime] requires >=13)
- Install torch CPU-only build separately in Dockerfile to avoid ~2GB CUDA download
- Remove torch from requirements.txt (installed via --index-url cpu wheel)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/services/voice-agent/Dockerfile

@@ -9,7 +9,8 @@ RUN apt-get update && apt-get install -y \
     && rm -rf /var/lib/apt/lists/*
 
 COPY requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
+RUN pip install --no-cache-dir torch --index-url https://download.pytorch.org/whl/cpu && \
+    pip install --no-cache-dir -r requirements.txt
 
 COPY src/ ./src/
 

packages/services/voice-agent/requirements.txt

@@ -5,10 +5,9 @@ livekit-plugins-openai>=1.0.0
 faster-whisper==1.2.1
 kokoro==0.3.5
 misaki[zh]==0.7.17
-websockets==12.0
+websockets>=13.0
 httpx==0.27.0
 numpy>=1.26.4
-torch>=2.0.0
 pydantic-settings==2.2.0
 ordered-set
 pypinyin