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)/graph-bfs/994-rotting-oranges.mdx

@@ -2,13 +2,15 @@
 title: '994. Rotting Oranges'
 description: 'You are given an m x n grid where each cell can have one of three values:'
 icon: dot
+topics:
+  - { name: "Array", slug: "array" }
+  - { name: "Breadth-First Search", slug: "breadth-first-search" }
+  - { name: "Matrix", slug: "matrix" }
 sidebar:
   label: 'Rotting Oranges'
   badge: 'Medium'
 ---
 
-<Badge variant="accent">Array</Badge>
-
 ### Example 1:
 - Input: `grid = [[2,1,1],[1,1,0],[0,1,1]]`
 - Output: `4`