fix: add chmod +x mvnw and fix git executable bit for Railway Docker build

Author: 11KAlYAN11

Dockerfile

@@ -9,6 +9,9 @@ WORKDIR /app
 COPY mvnw pom.xml ./
 COPY .mvn .mvn
 
+# Fix execute permission (lost when committed from Windows)
+RUN chmod +x mvnw
+
 # Download dependencies (cached layer)
 RUN ./mvnw dependency:go-offline -B