update challenge and homepaage

Author: kfahn22

content/pages/challenges/index.json

@@ -2,5 +2,5 @@
   "title": "Challenges",
   "description": "Ready to apply what you’ve learned in the Tracks? Try a Challenge! These one-off project videos build off concepts introduced in Tracks and may have prerequisites (listed on the challenge page itself).",
   "featuredText": "Featured Challenge:",
-  "featuredChallenge": "183-mathematical-marbling"
+  "featuredChallenge": "64-kinematics"
 }

content/pages/homepage/index.json

@@ -50,11 +50,11 @@
       "challenges/160-spring-forces/showcase/contribution-1717812105.json",
       "noc/4-particles/1-particle-system/showcase/contribution-1716063723.json",
       "challenges/183-mathematical-marbling/showcase/contribution-5.json",
-      "183-mathematical-marbling/showcase/contribution-1716187224.json",
+      "challenges/183-mathematical-marbling/showcase/contribution-1719747682.json",
       "challenges/93-double-pendulum/showcase/contribution-1717095241.json",
-      "",
-      "",
-      ""
+      "code/2-variables/5-map/showcase/contribution-1719881442.json",
+      "noc/3-angles/7-additive-waves/showcase/contribution-1719068587.json",
+      "challenges/10-dfs-maze-generator/showcase/contribution-1719932734.json"
     ],
     "showcaseCta": {
       "text": "Want to see more?",