Consistent hero layouts, activity page redesign, new content, and YouTube embeds

- Product pages (Code Editor, Robot Simulator): text-left/image-right hero layout
- Related resources capped at 3 items on all product pages
- Making Music activities renamed to I, II, III
- New Maze I/II/III and Sumo I/II/III difficulty-graded activities
- YouTube demo videos restored on 12 activity pages from old site
- Activity pages: two-column hero with coding skills & rover concepts tags
- Blog/news pages: same two-column hero layout with date
- Resource type extended with codingSkills, roverConcepts, tags fields
- Removed raw "Relevant Coding Skills/Rover Concepts" text from activity MDX

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

content/resources/lane-guidance.mdx

@@ -3,6 +3,8 @@ title: "Activity: Lane Guidance"
 date: "2021-06-03"
 categories: ["Activities", "All"]
 tags: ["Branching", "Iteration", "Algorithm Design", "Ultrasonic", "IR", "Motors", "Maths", "Advanced"]
+codingSkills: ["Branching", "Iteration", "Algorithm Design", "Maths"]
+roverConcepts: ["Ultrasonic", "IR", "Motors"]
 excerpt: "Learn iteration, branching, algorithm design, maths, and how to use the motors, ultrasonic, and IR sensors."
 featuredImage: "/images/resources/lane-guidance.png"
 ---
@@ -10,47 +12,9 @@ featuredImage: "/images/resources/lane-guidance.png"
 
 Program rovers to stay in the middle of a lane marked out by walls. This is a simplification of the lane assist technology in cars. Use the front ultrasonic sensor and both IR sensors on either side of the rover to determine where walls are and drive as smoothly through the middle of the path as you can. Don’t run into the walls!
 
-####
-  Relevant Coding Skills
+### Activity Demonstration
 
-    Branching
-
-    Iteration
-
-    Functions
-
-    Variables
-
-	-->
-
-    Algorithm Design
-
-    Maths
-
-####
-   Relevant Rover Concepts
-
-    Ultrasonic
-
-    IR
-
-    Colour
-
-    Gyroscope
-
-    Accelerometer
-
-    Motors
-
-    LEDs
-
-	-->
-
-    Buzzer
-
- 	-->
-
-Activity Demonstration
+<iframe width="560" height="315" src="https://www.youtube.com/embed/gK6SzjarP_U" title="Lane Guidance Activity Demonstration" frameBorder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowFullScreen></iframe>
 
 ### Setup