Refactor and secure backend configuration, DTOs, and authentication flow

- Updated pom.xml: removed redundant tags, grouped dependencies, added scopes, and upgraded plugins
- Enhanced RegisterUserDto with validation annotations and added missing fields (username, fullname)
- Updated User entity with builder constructor and removed redundant getters/setters
- Completed FileMetadata entity with Lombok and required setters/getters
- Improved HDFSConfig with correct annotation and clearer exception message
- Adjusted HTTP to HTTPS redirect port (8085 -> 8443)
- Allowed /actuator/** in SecurityConfig and disabled deprecated XSS protection
- Skipped JWT filter for /api/auth and /actuator paths
- Refactored AuthenticationService to use builder pattern and RSA key injection
- Fixed application.properties for static MySQL connection (removed ${MYSQL_PASSWORD})

src/main/java/com/skycrate/backend/skycrateBackend/config/SecurityConfig.java

@@ -29,7 +29,7 @@ public class SecurityConfig {
                 .sessionManagement(session -> session.sessionCreationPolicy(SessionCreationPolicy.STATELESS))
                 .authenticationProvider(authenticationProvider)
                 .authorizeHttpRequests(auth -> auth
-                        .requestMatchers("/api/auth/**").permitAll()
+                        .requestMatchers("/api/auth/**", "/actuator/**").permitAll()
                         .requestMatchers(HttpMethod.GET, "/public/**").permitAll()
                         .anyRequest().authenticated()
                 )
@@ -41,7 +41,8 @@ public class SecurityConfig {
                                 .includeSubDomains(true)
                                 .maxAgeInSeconds(31536000)
                         )
-                        .xssProtection(xss -> xss.block(true))
+                        // Spring Security 6+ no longer supports xss.block(true), so we just enable or disable it.
+                        .xssProtection(xss -> xss.disable())
                         .frameOptions(frame -> frame.deny())
                 )
                 .addFilterBefore(jwtAuthenticationFilter, UsernamePasswordAuthenticationFilter.class);