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/binary-search/0704-binary-search.org

@@ -1,18 +1,58 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0704. Binary Search :easy:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0704. Binary Search][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0704. Binary Search][0704. Binary Search]]
 :END:
 
+Given an array of integers ~nums~ which is sorted in ascending order, and an integer ~target~, write a function to search ~target~ in ~nums~. If ~target~ exists, then return its index. Otherwise, return ~-1~.
+
+You must write an algorithm with ~O(log n)~ runtime complexity.
+
+*Example 1:*
+
+
+#+begin_src
+Input: nums = [-1,0,3,5,9,12], target = 9
+Output: 4
+Explanation: 9 exists in nums and its index is 4
+#+end_src
+
+
+*Example 2:*
+
+
+#+begin_src
+Input: nums = [-1,0,3,5,9,12], target = 2
+Output: -1
+Explanation: 2 does not exist in nums so return -1
+#+end_src
+
+
+*Constraints:*
+
+ - ~1 <= nums.length <= 10^{4}~
+
+ - ~-10^{4} < nums[i], target < 10^{4}~
+
+ - All the integers in ~nums~ are *unique*.
+
+ - ~nums~ is sorted in ascending order.
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def search(self, nums: List[int], target: int) -> int:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    int search(vector<int>& nums, int target) {
+        
+    }
+};
 #+end_src