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/bit-manipulation/0371-sum-of-two-integers.org

@@ -1,18 +1,46 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0371. Sum of Two Integers :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0371. Sum of Two Integers][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0371. Sum of Two Integers][0371. Sum of Two Integers]]
 :END:
 
+Given two integers ~a~ and ~b~, return /the sum of the two integers without using the operators/ ~+~ /and/ ~-~.
+
+*Example 1:*
+
+
+#+begin_src
+Input: a = 1, b = 2
+Output: 3
+#+end_src
+*Example 2:*
+
+
+#+begin_src
+Input: a = 2, b = 3
+Output: 5
+#+end_src
+
+
+*Constraints:*
+
+ - ~-1000 <= a, b <= 1000~
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def getSum(self, a: int, b: int) -> int:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    int getSum(int a, int b) {
+        
+    }
+};
 #+end_src