docs: replace legacy line‑dot‑left‑horizontal icons with unified dot icon across docs

apps/docs/content/(01-linear-structures)/binary-search/74-search-a-2d-matrix.mdx

@@ -1,7 +1,7 @@
 ---
 title: '74. Search a 2D Matrix'
 description: 'You are given an m x n integer matrix matrix with the following two properties:'
-icon: line-dot-left-horizontal
+icon: dot
 sidebar:
   label: 'Search a 2D Matrix'
   badge: 'Medium'