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/0853-car-fleet.org

@@ -1,18 +1,86 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0853. Car Fleet :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0853. Car Fleet][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0853. Car Fleet][0853. Car Fleet]]
 :END:
 
+There are ~n~ cars at given miles away from the starting mile 0, traveling to reach the mile ~target~.
+
+You are given two integer arrays ~position~ and ~speed~, both of length ~n~, where ~position[i]~ is the starting mile of the ~i^{th}~ car and ~speed[i]~ is the speed of the ~i^{th}~ car in miles per hour.
+
+A car cannot pass another car, but it can catch up and then travel next to it at the speed of the slower car.
+
+A *car fleet* is a single car or a group of cars driving next to each other. The speed of the car fleet is the *minimum* speed of any car in the fleet.
+
+If a car catches up to a car fleet at the mile ~target~, it will still be considered as part of the car fleet.
+
+Return the number of car fleets that will arrive at the destination.
+
+*Example 1:*
+
+*Input:* target = 12, position = [10,8,0,5,3], speed = [2,4,1,1,3]
+
+*Output:* 3
+
+*Explanation:*
+
+ - The cars starting at 10 (speed 2) and 8 (speed 4) become a fleet, meeting each other at 12. The fleet forms at ~target~.
+
+ - The car starting at 0 (speed 1) does not catch up to any other car, so it is a fleet by itself.
+
+ - The cars starting at 5 (speed 1) and 3 (speed 3) become a fleet, meeting each other at 6. The fleet moves at speed 1 until it reaches ~target~.
+
+*Example 2:*
+
+*Input:* target = 10, position = [3], speed = [3]
+
+*Output:* 1
+
+*Explanation:*
+
+There is only one car, hence there is only one fleet.
+
+*Example 3:*
+
+*Input:* target = 100, position = [0,2,4], speed = [4,2,1]
+
+*Output:* 1
+
+*Explanation:*
+
+ - The cars starting at 0 (speed 4) and 2 (speed 2) become a fleet, meeting each other at 4. The car starting at 4 (speed 1) travels to 5.
+
+ - Then, the fleet at 4 (speed 2) and the car at position 5 (speed 1) become one fleet, meeting each other at 6. The fleet moves at speed 1 until it reaches ~target~.
+
+*Constraints:*
+
+ - ~n == position.length == speed.length~
+
+ - ~1 <= n <= 10^{5}~
+
+ - ~0 < target <= 10^{6}~
+
+ - ~0 <= position[i] < target~
+
+ - All the values of ~position~ are *unique*.
+
+ - ~0 < speed[i] <= 10^{6}~
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
-
+class Solution:
+    def carFleet(self, target: int, position: List[int], speed: List[int]) -> int:
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
-
+class Solution {
+public:
+    int carFleet(int target, vector<int>& position, vector<int>& speed) {
+        
+    }
+};
 #+end_src