feat: themes page implementation

[wlee261]

Description

Themes page according to figma specs

Closes #55

What change does this PR introduce?

Implements a themes page according to figma specs

Dark and light theme preview desktop

Dark and light theme desktop

Dark and light theme mobile

Dark and light theme preview mobile

Please select the relevant option(s).

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] CI/CD (updates related to the CI/CD process)
• [ ] Documentation update (changes to docs/code comments)
• [ ] Chore (miscellaneous tasks that do not fall into the above options)

What is the proposed approach?

Please give a short overview/explanation on the approach taken to resolve the issue(s).

Checklist:

• [ ] The commit message follows our adopted guidelines
• [ ] Testing has been done for the change(s) added (for bug fixes/features)
• [ ] Relevant comments/docs have been added/updated (for bug fixes/features)