Add Automated Java Code Formatting Check to Backend Workflow

[DenizAltunkapan]

Our Spring Boot backend currently has no enforced code formatting, which leads to inconsistent style across contributions. We should integrate a standard Java formatter (e.g., Google Java Format or Eclipse Formatter via Spotless) into the CI workflow. Every pull request should automatically run a formatting check and fail if the backend code is not properly formatted. This ensures consistent code style, simplifies reviews, and keeps the codebase clean.

[HarshMehta112]

@DenizAltunkapan Can I work on this ?

[rashmisoni2003]

@DenizAltunkapan can I also collaborate?

[DenizAltunkapan]

@rashmisoni2003 i will first assign @HarshMehta112 , if thats ok.