fix(ci): install curl in embedding-service image for healthcheck

python:3.12-slim does not include curl — every healthcheck attempt failed
silently, causing the container to be declared unhealthy after all retries.

embedding-service/Dockerfile

@@ -2,6 +2,8 @@ FROM python:3.12-slim
 
 WORKDIR /app
 
+RUN apt-get update && apt-get install -y --no-install-recommends curl && rm -rf /var/lib/apt/lists/*
+
 # Install dependencies first (cache layer)
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt