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/tries/0208-implement-trie-prefix-tree.org

@@ -1,18 +1,103 @@
 #+PROPERTY: STUDY_DECK_02
 * TODO 0208. Implement Trie Prefix Tree :medium:
 :PROPERTIES:
-:NEETCODE: [[file:../../roadmap.org::*0208. Implement Trie Prefix Tree][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0208. Implement Trie Prefix Tree][0208. Implement Trie Prefix Tree]]
 :END:
 
+A *trie* (pronounced as "try") or *prefix tree* is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker.
+
+Implement the Trie class:
+
+ - ~Trie()~ Initializes the trie object.
+
+ - ~void insert(String word)~ Inserts the string ~word~ into the trie.
+
+ - ~boolean search(String word)~ Returns ~true~ if the string ~word~ is in the trie (i.e., was inserted before), and ~false~ otherwise.
+
+ - ~boolean startsWith(String prefix)~ Returns ~true~ if there is a previously inserted string ~word~ that has the prefix ~prefix~, and ~false~ otherwise.
+
+*Example 1:*
+
+
+#+begin_src
+Input
+["Trie", "insert", "search", "search", "startsWith", "insert", "search"]
+[[], ["apple"], ["apple"], ["app"], ["app"], ["app"], ["app"]]
+Output
+[null, null, true, false, true, null, true]
+
+Explanation
+Trie trie = new Trie();
+trie.insert("apple");
+trie.search("apple");   // return True
+trie.search("app");     // return False
+trie.startsWith("app"); // return True
+trie.insert("app");
+trie.search("app");     // return True
+#+end_src
+
+
+*Constraints:*
+
+ - ~1 <= word.length, prefix.length <= 2000~
+
+ - ~word~ and ~prefix~ consist only of lowercase English letters.
+
+ - At most ~3 * 10^{4}~ calls *in total* will be made to ~insert~, ~search~, and ~startsWith~.
+
 ** TODO Approach
 Write your approach here.
 
 ** TODO Python
 #+begin_src python
+class Trie:
 
+    def __init__(self):
+        
+
+    def insert(self, word: str) -> None:
+        
+
+    def search(self, word: str) -> bool:
+        
+
+    def startsWith(self, prefix: str) -> bool:
+        
+
+
+# Your Trie object will be instantiated and called as such:
+# obj = Trie()
+# obj.insert(word)
+# param_2 = obj.search(word)
+# param_3 = obj.startsWith(prefix)
 #+end_src
 
 ** TODO C++
 #+begin_src cpp
+class Trie {
+public:
+    Trie() {
+        
+    }
+    
+    void insert(string word) {
+        
+    }
+    
+    bool search(string word) {
+        
+    }
+    
+    bool startsWith(string prefix) {
+        
+    }
+};
 
+/**
+ * Your Trie object will be instantiated and called as such:
+ * Trie* obj = new Trie();
+ * obj->insert(word);
+ * bool param_2 = obj->search(word);
+ * bool param_3 = obj->startsWith(prefix);
+ */
 #+end_src