Improve backend docker image size

backend/Dockerfile

@@ -1,10 +1,22 @@
-FROM python:3.11-slim AS base
+FROM python:3.11-slim AS builder
+WORKDIR /build
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    build-essential \
+ && rm -rf /var/lib/apt/lists/*
+
+COPY requirements.txt .
+RUN pip wheel --no-cache-dir --no-deps -r requirements.txt -w /build/wheels
+
+
+FROM python:3.11-slim
+WORKDIR /app
 
 # ---- Build args (desde Jenkins) ----
 ARG APP_VERSION=dev
 ARG GIT_COMMIT=local
 ARG COMMIT_AUTHOR=local
-ARG BUILD_NUMBER=—
+ARG BUILD_NUMBER=local
 
 # ---- Runtime env ----
 ENV APP_VERSION=${APP_VERSION} \
@@ -21,18 +33,10 @@ LABEL app.version="${APP_VERSION}" \
       git.author="${COMMIT_AUTHOR}" \
       build.number="${BUILD_NUMBER}"
 
-
-WORKDIR /app
-
-RUN apt-get update && apt-get install -y --no-install-recommends \
-      build-essential curl \
-    && rm -rf /var/lib/apt/lists/*
-
-COPY requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
+COPY --from=builder /build/wheels /wheels
+RUN pip install --no-cache-dir /wheels/* && rm -rf /wheels
 
 COPY app ./app
 
 EXPOSE 8000
-
 CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]