Add solution notes scaffold and sub-heading format

- roadmap.org: problems now have *** Python and *** C++ sub-headings,
  plus Notes: links to per-problem org files
- scaffold-notes.mjs: creates 199 note files in org/cpp/dsa/<topic>/
  with backlinks to roadmap.org
- 18 topic folders under org/cpp/dsa/ for NeetCode 150 problems
- Updated AGENTS.md with new conventions and workflow

org/cpp/dsa/arrays-hashing/0001-two-sum.org

@@ -0,0 +1,8 @@
+* TODO 0001. Two Sum :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0001. Two Sum][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/0036-valid-sudoku.org

@@ -0,0 +1,8 @@
+* TODO 0036. Valid Sudoku :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0036. Valid Sudoku][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/0049-group-anagrams.org

@@ -0,0 +1,8 @@
+* TODO 0049. Group Anagrams :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0049. Group Anagrams][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/0128-longest-consecutive-sequence.org

@@ -0,0 +1,8 @@
+* TODO 0128. Longest Consecutive Sequence :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0128. Longest Consecutive Sequence][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/0217-contains-duplicate.org

@@ -0,0 +1,8 @@
+* TODO 0217. Contains Duplicate :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0217. Contains Duplicate][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/0238-product-of-array-except-self.org

@@ -0,0 +1,8 @@
+* TODO 0238. Product of Array Except Self :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0238. Product of Array Except Self][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/0242-valid-anagram.org

@@ -0,0 +1,8 @@
+* TODO 0242. Valid Anagram :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0242. Valid Anagram][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/0271-encode-and-decode-strings.org

@@ -0,0 +1,8 @@
+* TODO 0271. Encode and Decode Strings :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0271. Encode and Decode Strings][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/0347-top-k-frequent-elements.org

@@ -0,0 +1,8 @@
+* TODO 0347. Top K Frequent Elements :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0347. Top K Frequent Elements][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/1408-string-matching-in-an-array.org

@@ -0,0 +1,8 @@
+* TODO 1408. String Matching in an Array :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*1408. String Matching in an Array][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/1769-minimum-number-of-operations-to-move-all-balls-to-each-box.org

@@ -0,0 +1,8 @@
+* TODO 1769. Minimum Number of Operations to Move All Balls to Each Box :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*1769. Minimum Number of Operations to Move All Balls to Each Box][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/arrays-hashing/2678-number-of-senior-citizens.org

@@ -0,0 +1,8 @@
+* TODO 2678. Number of Senior Citizens :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*2678. Number of Senior Citizens][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src