docs(docs): add ProblemBadges component, layout slot, and enrich pages with topics/video frontmatter, plus guide placeholders and topic‑landing map.

apps/docs/content/(04-relational)/topological-sort/207-course-schedule.mdx

@@ -2,13 +2,17 @@
 title: '207. Course Schedule'
 description: There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, bi] indicates that you must take course bi first if you want to take course ai
 icon: dot
+topics:
+  - { name: "Depth-First Search", slug: "depth-first-search" }
+  - { name: "Breadth-First Search", slug: "breadth-first-search" }
+  - { name: "Graph Theory", slug: "graph" }
+  - { name: "Topological Sort", slug: "topological-sort" }
+  - { name: "Directed Acyclic Graph", slug: "directed-acyclic-graph" }
 sidebar:
   label: 'Course Schedule'
   badge: 'Medium'
 ---
 
-<Badge variant="accent">Depth-First Search</Badge>
-
 ### Example 1:
 - Input: `numCourses = 2, prerequisites = [[1,0]]`
 - Output: `true`