chore: keep CLAUDE.md and package.json identical to main

A superset branch only stays cheap if the files it shares with main are
untouched. Both diverged: package.json carried a jd2 script and CLAUDE.md
described the tooling, so every merge from main would have conflicted on them
forever, and main's removal commit would have kept trying to delete the
tooling entries here.

The tooling files themselves do not exist on main, so they can hold whatever
they like. The jd2 invocation moves into docs/jdownloader.md as a direct npx
call instead of an npm script.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UXfdJu7QhSJLr47K7koTDF

package.json

@@ -12,8 +12,7 @@
     "clean": "rm -rf dist",
     "lint": "tsc --noEmit",
     "test": "vitest run",
-    "test:watch": "vitest",
-    "jd2": "tsx scripts/jd2-sync.ts"
+    "test:watch": "vitest"
   },
   "dependencies": {
     "@tailwindcss/vite": "^4.1.14",