fix: add file: prefix to org-mode links for Emacs resolution

Emorg org-mode requires [[file:path]] syntax for file links to be
clickable. Updated both extract.mjs and scaffold-notes.mjs generators,
and fixed all 200 existing note files.

leetcode/AGENTS.md

@@ -83,7 +83,7 @@ Scaffolded by `scaffold-notes.mjs`. Template:
 * TODO 0217. Contains Duplicate :easy:
 #+PROPERTY: STUDY_DECK_02
 :PROPERTIES:
-:NEETCODE: [[../../roadmap.org::*0217. Contains Duplicate][Roadmap]]
+:NEETCODE: [[file:../../roadmap.org::*0217. Contains Duplicate][Roadmap]]
 :END:
 
 #+begin_src cpp

leetcode/extract.mjs

@@ -248,7 +248,7 @@ function buildOrg(sortedNodes, problemsByTopic) {
       lines.push("");
       lines.push(`*** TODO Python`);
       lines.push(`*** TODO C++`);
-      lines.push(`Notes: [[${notesFile}]]`);
+      lines.push(`Notes: [[file:${notesFile}]]`);
     }
     lines.push("");
   }

leetcode/scaffold-notes.mjs

@@ -41,7 +41,7 @@ for (const line of roadmap.split("\n")) {
     const content = `* TODO ${num}. ${name} :${diff}:
 #+PROPERTY: STUDY_DECK_02
 :PROPERTIES:
-:NEETCODE: [[${relPath}][Roadmap]]
+:NEETCODE: [[file:${relPath}][Roadmap]]
 :END:
 
 ** TODO Approach