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/0207-course-schedule.org

@@ -1,18 +1,64 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0207. Course Schedule :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0207. Course Schedule][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0207. Course Schedule][0207. Course Schedule]]
 :END:
 
+There are a total of ~numCourses~ courses you have to take, labeled from ~0~ to ~numCourses - 1~. You are given an array ~prerequisites~ where ~prerequisites[i] = [a_{i}, b_{i}]~ indicates that you *must* take course ~b_{i}~ first if you want to take course ~a_{i}~.
+
+ - For example, the pair ~[0, 1]~, indicates that to take course ~0~ you have to first take course ~1~.
+
+Return ~true~ if you can finish all courses. Otherwise, return ~false~.
+
+*Example 1:*
+
+
+#+begin_src
+Input: numCourses = 2, prerequisites = [[1,0]]
+Output: true
+Explanation: There are a total of 2 courses to take. 
+To take course 1 you should have finished course 0. So it is possible.
+#+end_src
+
+
+*Example 2:*
+
+
+#+begin_src
+Input: numCourses = 2, prerequisites = [[1,0],[0,1]]
+Output: false
+Explanation: There are a total of 2 courses to take. 
+To take course 1 you should have finished course 0, and to take course 0 you should also have finished course 1. So it is impossible.
+#+end_src
+
+
+*Constraints:*
+
+ - ~1 <= numCourses <= 2000~
+
+ - ~0 <= prerequisites.length <= 5000~
+
+ - ~prerequisites[i].length == 2~
+
+ - ~0 <= a_{i}, b_{i} < numCourses~
+
+ - All the pairs prerequisites[i] are *unique*.
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def canFinish(self, numCourses: int, prerequisites: List[List[int]]) -> bool:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    bool canFinish(int numCourses, vector<vector<int>>& prerequisites) {
+        
+    }
+};
 #+end_src