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

apps/docs/content/(02-nodal-grid)/matrix-index-math/73-set-matrix-zeroes.mdx

@@ -2,13 +2,16 @@
 title: '73. Set Matrix Zeroes'
 description: Given an m x n integer matrix matrix, if an element is 0, set its entire row and column to 0's
 icon: dot
+topics:
+  - { name: "Array", slug: "array" }
+  - { name: "Hash Table", slug: "hash-table" }
+  - { name: "Matrix", slug: "matrix" }
+video: "T41rL0L3Pnw"
 sidebar:
   label: 'Set Matrix Zeroes'
   badge: 'Medium'
 ---
 
-<Badge variant="accent">Array</Badge>
-
 ::::warning
 You must do it in place.
 ::::
@@ -95,7 +98,3 @@ class Solution:
             for r in range(m):
                 matrix[r][0] = 0
 ```
-
-## Explanation
-
-<YouTube id="T41rL0L3Pnw" title="Set Matrix Zeroes - In-place - Leetcode 73" />