Improve cache busting

app/core/src/main/java/stirling/software/SPDF/config/WebMvcConfig.java

@@ -1,10 +1,14 @@
 package stirling.software.SPDF.config;
 
+import java.util.concurrent.TimeUnit;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.http.CacheControl;
 import org.springframework.web.servlet.config.annotation.CorsRegistry;
 import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
+import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
 import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
 
 import lombok.RequiredArgsConstructor;
@@ -25,6 +29,25 @@ public class WebMvcConfig implements WebMvcConfigurer {
         registry.addInterceptor(endpointInterceptor);
     }
 
+    @Override
+    public void addResourceHandlers(ResourceHandlerRegistry registry) {
+        // Cache hashed assets (JS/CSS with content hashes) for 1 year
+        // These files have names like index-ChAS4tCC.js that change when content changes
+        registry.addResourceHandler("/assets/**")
+                .addResourceLocations("classpath:/static/assets/")
+                .setCacheControl(CacheControl.maxAge(365, TimeUnit.DAYS).cachePublic());
+
+        // Don't cache index.html - it needs to be fresh to reference latest hashed assets
+        registry.addResourceHandler("/index.html")
+                .addResourceLocations("classpath:/static/")
+                .setCacheControl(CacheControl.noCache().mustRevalidate());
+
+        // Short cache for other static resources (images, fonts, etc.)
+        registry.addResourceHandler("/**")
+                .addResourceLocations("classpath:/static/")
+                .setCacheControl(CacheControl.maxAge(1, TimeUnit.HOURS).cachePublic());
+    }
+
     @Override
     public void addCorsMappings(CorsRegistry registry) {
         // Check if running in Tauri mode