style: updated overall app design for a cleaner and more consistent UI

docs: update documentaton

Refactor: Simplified 'Company' entity and extracted path constants to 'Constants' class for better modularity and maintainability.

chore(deps): upgrade Spring Boot to version 3.3.5 in pom.xml

docs: update project structure to include navbar and footer fragments

refactor: extract navbar and footer into Thymeleaf fragments for better modularity

Stop tracking the doc directory and add it to .gitignore

Added .gitignore file

Added home screen

Added model mapper

Updated diagrams on README.md doc

Polishing

Added messages.properties file to the README.md doc

Refactored

Updated README.md doc