installer-rp: delete base resourcepack zip after composing final pack

The RP installer downloads a fresh copy of the base zip into its temp
dir and composes the final pack on top of it. The base zip the main
installer placed in .mc_custom/resourcepacks/ has nothing to do after
that — but it stays in the Minecraft resource-pack list as a second
entry. Delete it after the final zip is written.

Guard against the case where the user set outputPackName equal to the
base filename, which would make base path == final path; in that case
we leave it alone so we don't wipe the file we just wrote.

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

locales/installer-rp/ko-kr.json

@@ -75,6 +75,7 @@
     "baseUrl": "  URL: {{url}}",
     "baseReceived": "베이스 리소스팩 받음 ({{kb}} KB)",
     "baseAbsent": "베이스 리소스팩 없음(resourcepackPath 빈 값) — 새 리소스팩으로 생성",
+    "baseRemoved": "베이스 리소스팩 삭제: {{path}}",
     "buildingZip": "리소스팩 zip 빌드 중… ({{name}})",
     "installComplete": "설치 완료: {{path}}",
     "cancelRequested": "취소 요청됨. 실행 중 프로세스 {{count}}개 중단…",