docs(docs): add Approach diagrams and Explanation sections to LeetCode problem documentation

apps/docs/content/(array)/48-rotate-image.mdx

@@ -22,6 +22,22 @@ sidebar:
 - `1 <= n <= 20`
 - `-1000 <= matrix[i][j] <= 1000`
 
+## Approach
+
+```mermaid
+flowchart TD
+  S(["rotate(matrix)"]) --> N["n = len(matrix)"]
+  N --> F{"more r in range(n)?"}
+  F -- yes --> G{"more c in range(r + 1, n)?"}
+  G -- yes --> T["swap matrix[r][c] and matrix[c][r] — transpose across the diagonal"]
+  T --> G
+  G -- no --> F
+  F -- no --> H{"more r in range(n)?"}
+  H -- yes --> R["matrix[r].reverse() — transpose then mirror is a clockwise turn"]
+  R --> H
+  H -- no --> E(["return None — rotated in place"])
+```
+
 ## Solution
 
 ```py
@@ -35,3 +51,7 @@ class Solution:
         for r in range(n):
             matrix[r].reverse()
 ```
+
+## Explanation
+
+<YouTube id="fMSJSS7eO1w" title="Rotate Image - Matrix - Leetcode 48" />