v4.0.0: 회원·덱 API, 인증 UI, 프로필 및 레이아웃 통일

Express/SQLite API와 Docker 구성을 추가하고 로그인·덱 저장·공개 덱·관리자·프로필 화면을 구현했다. 결과 화면 저장 UX, 헤더 프로필, 애드센스용 app-shell 레이아웃(1280px) 및 문서를 반영했다.

Co-authored-by: Cursor <cursoragent@cursor.com>

i18n/translations.en.json

@@ -20,7 +20,7 @@
     "editDeck": "← EDIT DECK",
     "deckPreview": "Deck Preview",
     "deckNameLabel": "Deck Name",
-    "deckNamePlaceholder": "Series name used if empty",
+    "deckNamePlaceholder": "YYYYMMDD_HHMMSS if empty",
     "exportStyle": "Export Style",
     "type1Title": "Type 1: Signature",
     "type1Desc": "Standard style highlighting Key Cards",
@@ -31,13 +31,21 @@
     "exportNotice1": "* If image fails to generate, please check 'Pop-up' settings.",
     "exportNotice2": "* On iOS, you may need to long-press the image to save.",
     "generatingImage": "Generating Image...",
+    "savingPreview": "Creating preview...",
+    "savingToMyDeck": "Saving to My Decks...",
+    "sharingDeck": "Creating share link...",
+    "saveComplete": "Saved!",
+    "shareComplete": "Ready to share!",
+    "downloadComplete": "Download complete!",
     "downloadImage": "DOWNLOAD IMAGE",
+    "saveToMyDeck": "Save to My Decks",
+    "shareDeck": "Share",
     "keyCardLabel": "KEY CARD",
     "back": "BACK",
     "saveError": "Failed to save image",
 
     "all": "All",
-    "metaDeck": "Meta Deck",
+    "metaDeck": "Public Decks",
     "titlePrompt": "Please select a title",
     "selectTitle": "Select Title",
     "deckName": "Deck Name",