chore: PC 설치파일명 DonDwaeji-Setup.exe + 기본 설치경로 DonDwaeji

- electron-builder artifactName: SlimBudget-Setup → DonDwaeji-Setup
- build/installer.nsh: 기본 설치경로를 $PROGRAMFILES\DonDwaeji 로 고정
  (productName 한글이라 name='sb_pt' 로 폴백되던 문제 회피)
- WebOnlyNotice 다운로드 URL 도 DonDwaeji-Setup.exe 로 변경

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

package.json

@@ -31,12 +31,13 @@
     "win": {
       "target": "nsis",
       "icon": "build/icon.ico",
-      "artifactName": "SlimBudget-Setup.${ext}"
+      "artifactName": "DonDwaeji-Setup.${ext}"
     },
     "nsis": {
       "oneClick": false,
       "perMachine": false,
-      "allowToChangeInstallationDirectory": true
+      "allowToChangeInstallationDirectory": true,
+      "include": "build/installer.nsh"
     }
   },
   "dependencies": {