Replace "FastNext" branding with "PragmaStack" across the project

- Updated all references, metadata, and templates to reflect the new branding, including layout files, components, and documentation.
- Replaced hardcoded color tokens like `green-600` with semantic tokens (`success`, `warning`, etc.) for improved design consistency.
- Enhanced `globals.css` with new color tokens for success, warning, and destructive states using the OKLCH color model.
- Added comprehensive branding guidelines and updated the design system documentation to align with the new identity.
- Updated tests and mocks to reflect the branding changes and ensured all visual/verbal references match "PragmaStack".
- Added new `branding/README.md` and `branding` docs for mission, values, and visual identity definition.

frontend/tests/app/page.test.tsx

@@ -1,6 +1,6 @@
 /**
  * Tests for Home Page
- * Tests for the new FastNext Template landing page
+ * Tests for the new PragmaStack landing page
  */
 
 import { render, screen, within, fireEvent } from '@testing-library/react';
@@ -59,14 +59,14 @@ describe('HomePage', () => {
     it('renders header with logo', () => {
       render(<Home />);
       const header = screen.getByRole('banner');
-      expect(within(header).getByText('FastNext')).toBeInTheDocument();
+      expect(within(header).getByText('PragmaStack')).toBeInTheDocument();
       expect(within(header).getByText('Template')).toBeInTheDocument();
     });
 
     it('renders footer with copyright', () => {
       render(<Home />);
       const footer = screen.getByRole('contentinfo');
-      expect(within(footer).getByText(/FastNext Template. MIT Licensed/i)).toBeInTheDocument();
+      expect(within(footer).getByText(/PragmaStack. MIT Licensed/i)).toBeInTheDocument();
     });
   });