Fix Dockerfile backend: usar FreeTDS en vez de driver MS (apt-key deprecado)

backend/Dockerfile

@@ -2,21 +2,21 @@ FROM python:3.11-slim
 
 WORKDIR /app
 
-# Dependencias del sistema necesarias para pyodbc (SQL Server) y psycopg2
+# Dependencias del sistema necesarias para pyodbc (via FreeTDS) y psycopg2
 RUN apt-get update && apt-get install -y --no-install-recommends \
     gcc \
     g++ \
     unixodbc \
     unixodbc-dev \
-    curl \
-    gnupg \
-    && curl https://packages.microsoft.com/keys/microsoft.asc | apt-key add - \
-    && curl https://packages.microsoft.com/config/debian/12/prod.list > /etc/apt/sources.list.d/mssql-release.list \
-    && apt-get update \
-    && ACCEPT_EULA=Y apt-get install -y --no-install-recommends msodbcsql18 \
+    freetds-dev \
+    freetds-bin \
+    tdsodbc \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/*
 
+# Registrar el driver FreeTDS bajo el nombre "SQL Server" (el que usa data_manager.py)
+RUN printf "[SQL Server]\nDescription = FreeTDS Driver\nDriver = /usr/lib/x86_64-linux-gnu/odbc/libtdsodbc.so\nSetup = /usr/lib/x86_64-linux-gnu/odbc/libtdsS.so\nFileUsage = 1\n" > /etc/odbcinst.ini
+
 COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt