Implement Advanced Theme Customization System

[MerlinTheWhiz]

Closes #102

Changes I made:

• themeUtils.ts — Added theme types, DEFAULT_THEME, presets, CSS var mapping, and validation.
• useThemeCustomization.tsx — Hook for theme state, localStorage, BroadcastChannel sync, and apply/import/export helpers.
• DynamicTheming.tsx — Client component to apply CSS variables at runtime.
• ThemePresets.tsx — UI to view and apply preset themes.
• ThemeCustomizer.tsx — Visual editor with live preview, apply/reset/copy/import using DEFAULT_THEME.
• ThemeExporter.tsx — UI for exporting (download) and importing themes (file input).
• layout.tsx — Mounted inside ThemeProvider for global CSS vars.
• page.tsx — Demo page rendering Customizer, Presets, and Exporter for testing.

Screenrecording:

Screencast.From.2026-03-28.15-17-32.mp4

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[RUKAYAT-CODER]

Please resolve conflict.
Support our project by giving us a star

[MerlinTheWhiz]

Please resolve conflict. Support our project by giving us a star

Hi @RUKAYAT-CODER , I already gave the project a star :)
I'll commence resolving conflicts now

[MerlinTheWhiz]

@RUKAYAT-CODER Conflicts has been resolved

Please consider me for future task assignments. Do you have a project community I can join? I'd like to get updates when you drop new issues

[RUKAYAT-CODER]

ok. Thank you for contributing to our project.
This is one Telegram group
https://t.me/teachlinkOD

[MerlinTheWhiz]

@RUKAYAT-CODER Thanks a lot, I just joined the telegram channel.