feat(boids): add boids and particle life demo

Add linkLabel to AlgorithmEntry. The info panel shows it instead of
"Wikipedia" when set, for links that are not Wikipedia.
Tick the boids item in ROADMAP.md and add a Boids 3D item.

src/app/constants/RouterConstants.ts

@@ -55,6 +55,11 @@
     LINK: '/algorithms/cloth',
   };
 
+  static readonly BOIDS = {
+    PATH: 'algorithms/boids',
+    LINK: '/algorithms/boids',
+  };
+
   static readonly FOUR_COLOR = {
     PATH: 'algorithms/four_color',
     LINK: '/algorithms/four_color',