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/linked-list/0002-add-two-numbers.org

@@ -0,0 +1,8 @@
+* TODO 0002. Add Two Numbers :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0002. Add Two Numbers][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0019-remove-nth-node-from-end-of-list.org

@@ -0,0 +1,8 @@
+* TODO 0019. Remove Nth Node From End of List :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0019. Remove Nth Node From End of List][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0021-merge-two-sorted-lists.org

@@ -0,0 +1,8 @@
+* TODO 0021. Merge Two Sorted Lists :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0021. Merge Two Sorted Lists][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0023-merge-k-sorted-lists.org

@@ -0,0 +1,8 @@
+* TODO 0023. Merge K Sorted Lists :hard:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0023. Merge K Sorted Lists][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0025-reverse-nodes-in-k-group.org

@@ -0,0 +1,8 @@
+* TODO 0025. Reverse Nodes In K Group :hard:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0025. Reverse Nodes In K Group][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0138-copy-list-with-random-pointer.org

@@ -0,0 +1,8 @@
+* TODO 0138. Copy List With Random Pointer :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0138. Copy List With Random Pointer][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0141-linked-list-cycle.org

@@ -0,0 +1,8 @@
+* TODO 0141. Linked List Cycle :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0141. Linked List Cycle][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0143-reorder-list.org

@@ -0,0 +1,8 @@
+* TODO 0143. Reorder List :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0143. Reorder List][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0146-lru-cache.org

@@ -0,0 +1,8 @@
+* TODO 0146. LRU Cache :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0146. LRU Cache][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0206-reverse-linked-list.org

@@ -0,0 +1,8 @@
+* TODO 0206. Reverse Linked List :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0206. Reverse Linked List][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0287-find-the-duplicate-number.org

@@ -0,0 +1,8 @@
+* TODO 0287. Find The Duplicate Number :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0287. Find The Duplicate Number][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/0725-split-linked-list-in-parts.org

@@ -0,0 +1,8 @@
+* TODO 0725. Split Linked List in Parts :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0725. Split Linked List in Parts][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/1472-design-browser-history.org

@@ -0,0 +1,8 @@
+* TODO 1472. Design Browser History :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*1472. Design Browser History][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/1721-swapping-nodes-in-a-linked-list.org

@@ -0,0 +1,8 @@
+* TODO 1721. Swapping Nodes in a Linked List :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*1721. Swapping Nodes in a Linked List][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/linked-list/2487-remove-nodes-from-linked-list.org

@@ -0,0 +1,8 @@
+* TODO 2487. Remove Nodes From Linked List :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*2487. Remove Nodes From Linked List][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src