Merge branch 'backend' into Front

.idea/.gitignore

.idea/compiler.xml

.idea/encodings.xml

.idea/jarRepositories.xml

.idea/misc.xml

.idea/modules.xml

.idea/quick-draw-project.iml

.idea/vcs.xml

README.md

backend/.gitattributes

backend/.gitignore

backend/.mvn/wrapper/maven-wrapper.properties

backend/mvnw

backend/mvnw.cmd

backend/pom.xml

backend/src/main/java/tse/backend/BackendApplication.java

...ava/tse/backend/application/BackendApplicationRunner.java

.../main/java/tse/backend/controller/CategoryController.java

...src/main/java/tse/backend/controller/ImageController.java

.../src/main/java/tse/backend/controller/UserController.java