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/0054-spiral-matrix.org

@@ -1,18 +1,54 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0054. Spiral Matrix :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0054. Spiral Matrix][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0054. Spiral Matrix][0054. Spiral Matrix]]
 :END:
 
+Given an ~m x n~ ~matrix~, return /all elements of the/ ~matrix~ /in spiral order/.
+
+*Example 1:*
+
+
+#+begin_src
+Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
+Output: [1,2,3,6,9,8,7,4,5]
+#+end_src
+
+
+*Example 2:*
+
+
+#+begin_src
+Input: matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
+Output: [1,2,3,4,8,12,11,10,9,5,6,7]
+#+end_src
+
+
+*Constraints:*
+
+ - ~m == matrix.length~
+
+ - ~n == matrix[i].length~
+
+ - ~1 <= m, n <= 10~
+
+ - ~-100 <= matrix[i][j] <= 100~
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    vector<int> spiralOrder(vector<vector<int>>& matrix) {
+        
+    }
+};
 #+end_src