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/stack/0682-baseball-game.org

@@ -1,18 +1,106 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0682. Baseball Game :easy:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0682. Baseball Game][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0682. Baseball Game][0682. Baseball Game]]
 :END:
 
+You are keeping the scores for a baseball game with strange rules. At the beginning of the game, you start with an empty record.
+
+You are given a list of strings ~operations~, where ~operations[i]~ is the ~i^{th}~ operation you must apply to the record and is one of the following:
+
+ - An integer ~x~.
+
+ - Record a new score of ~x~.
+
+ - ~'+'~.
+ 
+ - Record a new score that is the sum of the previous two scores.
+
+ - ~'D'~.
+ 
+ - Record a new score that is the double of the previous score.
+
+ - ~'C'~.
+ 
+ - Invalidate the previous score, removing it from the record.
+
+Return /the sum of all the scores on the record after applying all the operations/.
+
+The test cases are generated such that the answer and all intermediate calculations fit in a *32-bit* integer and that all operations are valid.
+
+*Example 1:*
+
+
+#+begin_src
+Input: ops = ["5","2","C","D","+"]
+Output: 30
+Explanation:
+"5" - Add 5 to the record, record is now [5].
+"2" - Add 2 to the record, record is now [5, 2].
+"C" - Invalidate and remove the previous score, record is now [5].
+"D" - Add 2 * 5 = 10 to the record, record is now [5, 10].
+"+" - Add 5 + 10 = 15 to the record, record is now [5, 10, 15].
+The total sum is 5 + 10 + 15 = 30.
+#+end_src
+
+
+*Example 2:*
+
+
+#+begin_src
+Input: ops = ["5","-2","4","C","D","9","+","+"]
+Output: 27
+Explanation:
+"5" - Add 5 to the record, record is now [5].
+"-2" - Add -2 to the record, record is now [5, -2].
+"4" - Add 4 to the record, record is now [5, -2, 4].
+"C" - Invalidate and remove the previous score, record is now [5, -2].
+"D" - Add 2 * -2 = -4 to the record, record is now [5, -2, -4].
+"9" - Add 9 to the record, record is now [5, -2, -4, 9].
+"+" - Add -4 + 9 = 5 to the record, record is now [5, -2, -4, 9, 5].
+"+" - Add 9 + 5 = 14 to the record, record is now [5, -2, -4, 9, 5, 14].
+The total sum is 5 + -2 + -4 + 9 + 5 + 14 = 27.
+#+end_src
+
+
+*Example 3:*
+
+
+#+begin_src
+Input: ops = ["1","C"]
+Output: 0
+Explanation:
+"1" - Add 1 to the record, record is now [1].
+"C" - Invalidate and remove the previous score, record is now [].
+Since the record is empty, the total sum is 0.
+#+end_src
+
+
+*Constraints:*
+
+ - ~1 <= operations.length <= 1000~
+
+ - ~operations[i]~ is ~"C"~, ~"D"~, ~"+"~, or a string representing an integer in the range ~[-3 * 10^{4}, 3 * 10^{4}]~.
+
+ - For operation ~"+"~, there will always be at least two previous scores on the record.
+
+ - For operations ~"C"~ and ~"D"~, there will always be at least one previous score on the record.
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def calPoints(self, operations: List[str]) -> int:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    int calPoints(vector<string>& operations) {
+        
+    }
+};
 #+end_src