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/1-d-dynamic-programming/0322-coin-change.org

@@ -1,18 +1,66 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0322. Coin Change :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0322. Coin Change][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0322. Coin Change][0322. Coin Change]]
 :END:
 
+You are given an integer array ~coins~ representing coins of different denominations and an integer ~amount~ representing a total amount of money.
+
+Return /the fewest number of coins that you need to make up that amount/. If that amount of money cannot be made up by any combination of the coins, return ~-1~.
+
+You may assume that you have an infinite number of each kind of coin.
+
+*Example 1:*
+
+
+#+begin_src
+Input: coins = [1,2,5], amount = 11
+Output: 3
+Explanation: 11 = 5 + 5 + 1
+#+end_src
+
+
+*Example 2:*
+
+
+#+begin_src
+Input: coins = [2], amount = 3
+Output: -1
+#+end_src
+
+
+*Example 3:*
+
+
+#+begin_src
+Input: coins = [1], amount = 0
+Output: 0
+#+end_src
+
+
+*Constraints:*
+
+ - ~1 <= coins.length <= 12~
+
+ - ~1 <= coins[i] <= 2^{31} - 1~
+
+ - ~0 <= amount <= 10^{4}~
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def coinChange(self, coins: List[int], amount: int) -> int:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    int coinChange(vector<int>& coins, int amount) {
+        
+    }
+};
 #+end_src