feat: implement video site per README spec

- Express + EJS + express-session stack (auth/navbar ported from minecraft_launcher)
- Public: main folder list, folder video grid, internal popup player (/player/:videoId)
- Admin (/op): login, folder CRUD with right-click context menu + add-folder modal
- Admin folder: video grid with right-click edit/rename/delete, "영상 추가" -> editor
- Video editor: drag-drop upload, file picker, YouTube URL probe (ETA + 5분 경고),
  background yt-dlp download with progress polling, navbar title edit, trim controls,
  save runs ffmpeg trim (original preserved)
- Filesystem storage under data/folders/<name>/<videoId>/{meta.json, original.<ext>, edited.<ext>}

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

package.json

@@ -0,0 +1,26 @@
+{
+  "name": "make-video-site",
+  "version": "0.1.0",
+  "description": "영상 업로드 및 저장을 위한 사이트",
+  "type": "module",
+  "main": "dist/app.js",
+  "scripts": {
+    "build": "tsc -p tsconfig.json",
+    "start": "node dist/app.js",
+    "dev": "tsc -p tsconfig.json && node dist/app.js"
+  },
+  "dependencies": {
+    "ejs": "^3.1.10",
+    "express": "^4.19.2",
+    "express-session": "^1.18.0",
+    "multer": "^1.4.5-lts.1"
+  },
+  "devDependencies": {
+    "@types/ejs": "^3.1.5",
+    "@types/express": "^4.17.21",
+    "@types/express-session": "^1.18.0",
+    "@types/multer": "^1.4.11",
+    "@types/node": "^22.5.0",
+    "typescript": "^5.5.4"
+  }
+}