refactor: move DSA notes to org/study_deck_02/

Restructure NeetCode study materials into a dedicated Anki-exportable
deck directory. Separates DSA problem notes from C++ flashcards.

- Move roadmap.org from leetcode/out/ to org/study_deck_02/
- Move 200 note files from org/cpp/dsa/ to org/study_deck_02/dsa/
- Add #+PROPERTY: STUDY_DECK_02 to all org files for org-anki export
- Simplify roadmap format: properties drawer replaces nested headings
- Update NEETCODE backlinks in all note files
- Update extract.mjs and scaffold-notes.mjs for new paths
- Create org/study_deck_02/AGENTS.md with study workflow docs
- Update root and leetcode AGENTS.md

leetcode/extract.mjs

@@ -197,6 +197,7 @@ function buildOrg(sortedNodes, problemsByTopic) {
   const now = new Date().toISOString().slice(0, 10);
 
   lines.push("#+TITLE: NeetCode Roadmap");
+  lines.push("#+PROPERTY: STUDY_DECK_02");
   lines.push(`#+DATE: ${now}`);
   lines.push("#+TODO: TODO DONE");
   lines.push("#+STARTUP: overview");
@@ -213,7 +214,7 @@ function buildOrg(sortedNodes, problemsByTopic) {
       .replace(/[^a-z0-9]+/g, "-")
       .replace(/(^-|-$)/g, "");
 
-  const notesRoot = "../../org/cpp/dsa";
+  const notesRoot = "dsa";
 
   for (const node of sortedNodes) {
     const topicProblems = (problemsByTopic[node.name] || []).filter(
@@ -234,17 +235,17 @@ function buildOrg(sortedNodes, problemsByTopic) {
       const lcUrl = `${LEETCODE_BASE}${p.link}`;
       const num = p.code.split("-")[0];
       const notesFile = `${notesRoot}/${slug}/${p.code}.org`;
-      lines.push(`** TODO ${num}. ${p.name} :${tag}: [/]`);
-      lines.push(`*** TODO Python`);
-      lines.push(`- [[${GITHUB_SOLUTIONS}python/${p.code}.py][${p.code}.py]]`);
-      lines.push(`*** TODO C++`);
-      lines.push(`- [[${GITHUB_SOLUTIONS}cpp/${p.code}.cpp][${p.code}.cpp]]`);
-      lines.push(`- LeetCode: [[${lcUrl}][${p.link}]]`);
+      lines.push(`** TODO ${num}. ${p.name} :${tag}:`);
+      lines.push(`:PROPERTIES:`);
+      lines.push(`:LEETCODE: [[${lcUrl}][Problem]]`);
+      lines.push(`:CPP:      [[${GITHUB_SOLUTIONS}cpp/${p.code}.cpp][Solution]]`);
+      lines.push(`:PYTHON:   [[${GITHUB_SOLUTIONS}python/${p.code}.py][Solution]]`);
       if (p.video)
         lines.push(
-          `- Video: [[https://youtube.com/watch?v=${p.video}][explanation]]`
+          `:VIDEO:    [[https://youtube.com/watch?v=${p.video}][Watch]]`
         );
-      lines.push(`- Notes: [[${notesFile}][My Solution]]`);
+      lines.push(`:END:`);
+      lines.push(`Notes: [[${notesFile}][My Solution]]`);
     }
     lines.push("");
   }
@@ -343,9 +344,11 @@ async function main() {
     // DOT
     writeFileSync(join(outDir, "roadmap.dot"), buildDot(nodes), "utf8");
 
-    // Org-mode
+    // Org-mode — write to org/study_deck_02/roadmap.org
+    const orgDir = join(__dirname, "../org/study_deck_02");
+    mkdirSync(orgDir, { recursive: true });
     writeFileSync(
-      join(outDir, "roadmap.org"),
+      join(orgDir, "roadmap.org"),
       buildOrg(sorted, problemsByTopic),
       "utf8"
     );
@@ -353,7 +356,7 @@ async function main() {
     console.log(`Wrote ${outDir}/roadmap.json        (${result.stats.totalProblems} problems total)`);
     console.log(`Wrote ${outDir}/roadmap-neetcode150.json (${result.stats.neetcode150} problems)`);
     console.log(`Wrote ${outDir}/roadmap.dot`);
-    console.log(`Wrote ${outDir}/roadmap.org`);
+    console.log(`Wrote ${join(orgDir, "roadmap.org")}`);
     console.log(
       `  ${result.stats.topics} topics, ${result.stats.edges} edges`
     );