align dependency runtime baselines across Docker and CI

backend/Dockerfile

@@ -1,5 +1,6 @@
 # Stage 1: Build stage with dependencies
-FROM python:3.13-slim AS builder
+ARG PYTHON_IMAGE=python:3.13-slim
+FROM ${PYTHON_IMAGE} AS builder
 
 # Metadata labels
 LABEL maintainer="Voyage contributors" \
@@ -35,7 +36,7 @@ RUN pip install --upgrade pip \
     && pip install --no-cache-dir -r requirements.txt
 
 # Stage 2: Final image with runtime dependencies
-FROM python:3.13-slim
+FROM ${PYTHON_IMAGE}
 WORKDIR /code
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONUNBUFFERED=1

backend/server/requirements.txt

@@ -33,5 +33,5 @@ legacy-cgi==2.6.4
 requests>=2.32.5
 cryptography>=46.0.5
 django-mcp-server>=0.5.7
-litellm>=1.82.1
-duckduckgo-search>=4.0.0
+litellm>=1.82.2
+duckduckgo-search>=8.1.1