Expand Saxon extension functions

backend/Dockerfile

@@ -2,7 +2,7 @@
 FROM golang:1.23-alpine AS builder
 
 # Instalar dependencias necesarias
-RUN apk add --no-cache git
+RUN apk add --no-cache git openjdk17
 
 # Establecer directorio de trabajo
 WORKDIR /app/src
@@ -18,6 +18,14 @@ RUN go mod init xslt-playground && \
     go mod tidy && \
     go build -o server .
 
+# Build extension functions jar
+WORKDIR /app/ext
+COPY ext/ .
+RUN javac com/xsltplayground/ext/CustomFunctions.java && \
+    jar cf custom-functions.jar com/xsltplayground/ext/CustomFunctions.class
+
+WORKDIR /app/src
+
 # Etapa final (runtime)
 FROM alpine:latest
 
@@ -36,6 +44,9 @@ RUN mkdir -p /opt/saxon && \
     curl -L -o /opt/saxon/saxon-he.jar https://repo1.maven.org/maven2/net/sf/saxon/Saxon-HE/11.6/Saxon-HE-11.6.jar && \
     curl -L -o /opt/saxon/xmlresolver.jar https://repo1.maven.org/maven2/org/xmlresolver/xmlresolver/4.5.0/xmlresolver-4.5.0.jar
 
+# Extension functions jar
+COPY --from=builder /app/ext/custom-functions.jar /opt/saxon/
+
 
 # Exponer el puerto por defecto y ejecutar el binario
 EXPOSE 8000