installer-rp: site-configured outputPackName for built zip

Adds a new "생성되는 리소스팩 이름" admin field saved to the pack
manifest and consumed by the rp installer when naming the final zip.
Empty value falls back to <packKey>_musicquiz; Windows-invalid chars
are sanitized to '_'. Bumps version 0.1.1 → 0.2.0 (new feature).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "minecraft-music-quiz-installer",
-  "version": "0.1.1",
+  "version": "0.2.0",
   "description": "마인크래프트 음악퀴즈 간편설치기 + 관리 사이트",
   "main": "dist/installer/main.js",
   "scripts": {