Light mode & dark mode theming

[root458]

Description

This PR:

• Sets up light mode and dark mode theming, initiates Light theme & dark theme #90
• The change starts with the About page. Sample previews are shown below.

Light Theme

Dark Theme

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

Test Changes on Device

You can download your APK from Firebase App Distribution once this PR builds successfully via the following link: https://appdistribution.firebase.dev/i/c796669942f8a811

[MillerAdulu]

Do proceed with this approach. Superb!

[MillerAdulu]

@root458,

Needing to kickstart work on #89. So proceeding to merge this in, then you can branch out and continue the work and every page can be it's own.

You can work on the speaker details page and the session details page for dark mode. I should hopefully be done with the data-loading issue before the night ends and have it merged in so that the dark mode work isn't badly behind. I should be available for a bit longer tonight in case anything isn't as clear or you have any doubts. Again a need for constant comms at this stage to prevent unpleasant merge conflicts.

[root458]

Got it @MillerAdulu,

I'll pull the new changes from main and continue.