feat: populate note files with problem descriptions and code stubs

Add populate-notes.mjs that fetches problem descriptions and
Python/C++ code stubs from LeetCode's GraphQL API. Populated
all 197 NeetCode 150 note files with:
- Problem description (examples, constraints)
- Python code stub (function signature)
- C++ code stub (function signature + includes)

API responses cached in leetcode/.cache/leetcode/ for instant re-runs.

org/study_deck_02/dsa/math-geometry/0048-rotate-image.org

@@ -1,18 +1,57 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0048. Rotate Image :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0048. Rotate Image][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0048. Rotate Image][0048. Rotate Image]]
 :END:
 
+You are given an ~n x n~ 2D ~matrix~ representing an image, rotate the image by *90* degrees (clockwise).
+
+You have to rotate the image *in-place*, which means you have to modify the input 2D matrix directly. *DO NOT* allocate another 2D matrix and do the rotation.
+
+*Example 1:*
+
+
+#+begin_src
+Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
+Output: [[7,4,1],[8,5,2],[9,6,3]]
+#+end_src
+
+
+*Example 2:*
+
+
+#+begin_src
+Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
+Output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]
+#+end_src
+
+
+*Constraints:*
+
+ - ~n == matrix.length == matrix[i].length~
+
+ - ~1 <= n <= 20~
+
+ - ~-1000 <= matrix[i][j] <= 1000~
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def rotate(self, matrix: List[List[int]]) -> None:
+        """
+        Do not return anything, modify matrix in-place instead.
+        """
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    void rotate(vector<vector<int>>& matrix) {
+        
+    }
+};
 #+end_src