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/graphs/0200-number-of-islands.org

@@ -1,18 +1,66 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0200. Number of Islands :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0200. Number of Islands][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0200. Number of Islands][0200. Number of Islands]]
 :END:
 
+Given an ~m x n~ 2D binary grid ~grid~ which represents a map of ~'1'~s (land) and ~'0'~s (water), return /the number of islands/.
+
+An *island* is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.
+
+*Example 1:*
+
+
+#+begin_src
+Input: grid = [
+  ["1","1","1","1","0"],
+  ["1","1","0","1","0"],
+  ["1","1","0","0","0"],
+  ["0","0","0","0","0"]
+]
+Output: 1
+#+end_src
+
+
+*Example 2:*
+
+
+#+begin_src
+Input: grid = [
+  ["1","1","0","0","0"],
+  ["1","1","0","0","0"],
+  ["0","0","1","0","0"],
+  ["0","0","0","1","1"]
+]
+Output: 3
+#+end_src
+
+
+*Constraints:*
+
+ - ~m == grid.length~
+
+ - ~n == grid[i].length~
+
+ - ~1 <= m, n <= 300~
+
+ - ~grid[i][j]~ is ~'0'~ or ~'1'~.
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def numIslands(self, grid: List[List[str]]) -> int:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    int numIslands(vector<vector<char>>& grid) {
+        
+    }
+};
 #+end_src