feat(ui): add floating info button to reopen modal and enforce single-session flow

fix(ui): enhance modal styling, navbar color, form validation and session logic

feat(ui): add navbar with home and profile links

style: improved card alignment and responsiveness in templates

style: make chat layout responsive for screens smaller than 1100px

style: apply genre grid layout and improve form spacing

feat(start): allow toggling between new profile creation and existing profiles list

feat: add custom stylesheet for improved UI