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/sliding-window/0003-longest-substring-without-repeating-characters.org

@@ -0,0 +1,8 @@
+* TODO 0003. Longest Substring Without Repeating Characters :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0003. Longest Substring Without Repeating Characters][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/sliding-window/0076-minimum-window-substring.org

@@ -0,0 +1,8 @@
+* TODO 0076. Minimum Window Substring :hard:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0076. Minimum Window Substring][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/sliding-window/0121-best-time-to-buy-and-sell-stock.org

@@ -0,0 +1,8 @@
+* TODO 0121. Best Time to Buy And Sell Stock :easy:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0121. Best Time to Buy And Sell Stock][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/sliding-window/0239-sliding-window-maximum.org

@@ -0,0 +1,8 @@
+* TODO 0239. Sliding Window Maximum :hard:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0239. Sliding Window Maximum][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/sliding-window/0424-longest-repeating-character-replacement.org

@@ -0,0 +1,8 @@
+* TODO 0424. Longest Repeating Character Replacement :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0424. Longest Repeating Character Replacement][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/sliding-window/0567-permutation-in-string.org

@@ -0,0 +1,8 @@
+* TODO 0567. Permutation In String :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*0567. Permutation In String][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src

org/cpp/dsa/sliding-window/3306-count-of-substrings-containing-every-vowel-and-k-consonants-ii.org

@@ -0,0 +1,8 @@
+* TODO 3306. Count of Substrings Containing Every Vowel and K Consonants II :medium:
+:PROPERTIES:
+:NEETCODE: [[../../../../leetcode/out/roadmap.org::*3306. Count of Substrings Containing Every Vowel and K Consonants II][Roadmap]]
+:END:
+
+#+begin_src cpp
+
+#+end_src