feat(fourier): add epicycles algorithm demo

Draw a shape or pick a preset, then rebuild it with a direct DFT.
Each frequency becomes one circle. Circles are sorted by radius, and
the circles slider keeps the biggest N. Also tick the ROADMAP item and
add the FOURIER SEO key.

src/app/app.routes.ts

@@ -16,6 +16,7 @@ export const routes: Routes = [
   { path: RouterConstants.PENDULUM.PATH, loadComponent: () => import('./pages/algorithms/pendulum/pendulum.component').then(m => m.default), data: { seo: 'ALGORITHMS' } },
   { path: RouterConstants.CLOTH.PATH, loadComponent: () => import('./pages/algorithms/cloth/cloth.component').then(m => m.ClothComponent), data: { seo: 'ALGORITHMS' } },
   { path: RouterConstants.FOUR_COLOR.PATH, loadComponent: () => import('./pages/algorithms/four-color/four-color.component').then(m => m.FourColorComponent), data: { seo: 'ALGORITHMS' } },
+  { path: RouterConstants.FOURIER.PATH, loadComponent: () => import('./pages/algorithms/fourier/fourier.component').then(m => m.FourierComponent), data: { seo: 'FOURIER' } },
   { path: RouterConstants.STOPWATCH.PATH, loadComponent: () => import('./pages/stopwatch/stopwatch.component').then(m => m.StopwatchComponent), data: { seo: 'STOPWATCH' } },
   { path: '**', loadComponent: () => import('./pages/not-found/not-found.component').then(m => m.NotFoundComponent), data: { seo: 'NOT_FOUND' } },
 ];