feat: Migrate from CoreUI to Material UI (MUI)

[devin-ai-integration]

Summary

This PR performs a complete migration of the React admin template from CoreUI to Material UI (MUI). The migration includes replacing all CoreUI components with MUI equivalents, updating the theming system, migrating from SCSS to MUI's sx prop styling, and switching the charting library from Chart.js to Recharts.

Key changes:

• Replaced CoreUI dependencies with MUI packages (@mui/material, @mui/icons-material, @emotion/react, @emotion/styled)
• Created new MUI theme configuration with light/dark mode support via ThemeProvider
• Migrated all layout components (DefaultLayout, AppHeader, AppSidebar, AppFooter, AppContent) to use MUI components
• Implemented MUI responsive Drawer for sidebar navigation
• Migrated all 40+ component demo pages (base, buttons, forms, notifications, icons, charts, etc.)
• Added loading states with CircularProgress and Fade transitions
• Removed all SCSS files and migrated styling to MUI's sx prop approach
• Replaced Chart.js with Recharts for data visualization

Review & Testing Checklist for Human

This is a high-risk PR due to the scope of changes (75 files, complete UI library replacement). Please verify:

• Run the app locally (npm start) and verify all pages render without console errors
• Test sidebar navigation - verify responsive drawer behavior on mobile/tablet/desktop breakpoints, test collapse/expand functionality
• Verify theme switching - test light/dark mode toggle in the header works correctly and persists
• Test form validation - navigate to Forms > Validation and verify real-time validation feedback works
• Check charts rendering - verify Dashboard charts and Charts page display correctly with Recharts

Recommended test plan:

1. Run npm install then npm start
2. Navigate through all sidebar menu items to verify each page loads
3. Test responsive behavior by resizing browser window
4. Toggle theme between light and dark modes
5. Test interactive components (modals, dropdowns, accordions, tabs)
6. Submit the validation form with invalid/valid data

Notes

• The MainChart component now uses static demo data instead of random values (required to fix React purity lint error)
• Some PRO-only features that linked to external CoreUI docs are preserved as external links
• The navigation structure in _nav.js was simplified to use plain objects instead of CoreUI components

Link to Devin run: https://partner-workshops.devinenterprise.com/sessions/b4494ace1929447880a56fba49a2bb61
Requested by: krishnan.tn@cognizant.com

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring