refactor: 完全重构为 Anki 兼容数据结构

- 用 Deck 替换 Folder
- 用 Note + Card 替换 Pair (双向复习)
- 添加 NoteType (卡片模板)
- 添加 Revlog (复习历史)
- 实现 SM-2 间隔重复算法
- 更新所有前端页面
- 添加数据库迁移

messages/en-US.json

@@ -169,22 +169,46 @@
     "resetPasswordSuccessHint": "Your password has been reset successfully. You can now log in with your new password."
   },
   "memorize": {
-    "folder_selector": {
-      "selectFolder": "Select a folder",
-      "noFolders": "No folders found",
-      "folderInfo": "{id}. {name} ({count})"
+    "deck_selector": {
+      "selectDeck": "Select a deck",
+      "noDecks": "No decks found",
+      "goToDecks": "Go to Decks",
+      "noCards": "No cards",
+      "new": "New",
+      "learning": "Learning",
+      "review": "Review",
+      "due": "Due"
     },
-    "memorize": {
-      "answer": "Answer",
-      "next": "Next",
-      "reverse": "Reverse",
-      "dictation": "Dictation",
-      "noTextPairs": "No text pairs available",
-      "disorder": "Disorder",
-      "previous": "Previous"
+    "review": {
+      "loading": "Loading cards...",
+      "backToDecks": "Back to Decks",
+      "allDone": "All Done!",
+      "allDoneDesc": "You've reviewed all due cards.",
+      "reviewedCount": "Reviewed {count} cards",
+      "progress": "{current} / {total}",
+      "nextReview": "Next review",
+      "interval": "Interval",
+      "ease": "Ease",
+      "lapses": "Lapses",
+      "showAnswer": "Show Answer",
+      "again": "Again",
+      "hard": "Hard",
+      "good": "Good",
+      "easy": "Easy",
+      "now": "now",
+      "lessThanMinute": "<1 min",
+      "inMinutes": "{count} min",
+      "inHours": "{count}h",
+      "inDays": "{count}d",
+      "inMonths": "{count}mo",
+      "minutes": "<1 min",
+      "days": "{count}d",
+      "months": "{count}mo",
+      "minAbbr": "m",
+      "dayAbbr": "d"
     },
     "page": {
-      "unauthorized": "You are not authorized to access this folder"
+      "unauthorized": "You are not authorized to access this deck"
     }
   },
   "navbar": {
@@ -200,31 +224,45 @@
   "ocr": {
     "title": "OCR Vocabulary Extractor",
     "description": "Upload vocabulary table screenshots from textbooks to extract word-definition pairs",
+    "uploadSection": "Upload Image",
     "uploadImage": "Upload Image",
     "dragDropHint": "Drag and drop an image here, or click to select",
+    "dropOrClick": "Drag and drop an image here, or click to select",
+    "changeImage": "Click to change image",
     "supportedFormats": "Supports: JPG, PNG, WebP",
-    "selectFolder": "Select Folder",
-    "chooseFolder": "Choose a folder to save extracted pairs",
-    "noFolders": "No folders available. Please create a folder first.",
+    "deckSelection": "Select Deck",
+    "selectDeck": "Select a deck",
+    "chooseDeck": "Choose a deck to save extracted pairs",
+    "noDecks": "No decks available. Please create a deck first.",
     "languageHints": "Language Hints (Optional)",
     "sourceLanguageHint": "Source language (e.g., English)",
     "targetLanguageHint": "Target/Translation language (e.g., Chinese)",
+    "sourceLanguagePlaceholder": "Source language (e.g., English)",
+    "targetLanguagePlaceholder": "Target/Translation language (e.g., Chinese)",
     "process": "Process Image",
+    "processButton": "Process Image",
     "processing": "Processing...",
     "preview": "Preview",
-    "extractedPairs": "Extracted Pairs",
+    "resultsPreview": "Results Preview",
+    "extractedPairs": "Extracted {count} pairs",
     "word": "Word",
     "definition": "Definition",
     "pairsCount": "{count} pairs extracted",
-    "savePairs": "Save to Folder",
+    "savePairs": "Save to Deck",
+    "saveButton": "Save",
     "saving": "Saving...",
-    "saved": "Successfully saved {count} pairs to {folder}",
+    "saved": "Successfully saved {count} pairs to {deck}",
+    "ocrSuccess": "Successfully extracted {count} pairs to {deck}",
+    "savedToDeck": "Saved to {deckName}",
     "saveFailed": "Failed to save pairs",
     "noImage": "Please upload an image first",
-    "noFolder": "Please select a folder",
+    "noDeck": "Please select a deck",
+    "noResultsToSave": "No results to save",
     "processingFailed": "OCR processing failed",
     "tryAgain": "Please try again with a clearer image",
-    "detectedLanguages": "Detected: {source} → {target}"
+    "detectedLanguages": "Detected: {source} → {target}",
+    "detectedSourceLanguage": "Detected source language",
+    "detectedTargetLanguage": "Detected target language"
   },
   "profile": {
     "myProfile": "My Profile",
@@ -338,11 +376,11 @@
   },
   "explore": {
     "title": "Explore",
-    "subtitle": "Discover public folders",
-    "searchPlaceholder": "Search public folders...",
+    "subtitle": "Discover public decks",
+    "searchPlaceholder": "Search public decks...",
     "loading": "Loading...",
-    "noFolders": "No public folders found",
-    "folderInfo": "{userName} • {totalPairs} pairs",
+    "noDecks": "No public decks found",
+    "deckInfo": "{userName} • {cardCount} cards",
     "unknownUser": "Unknown User",
     "favorite": "Favorite",
     "unfavorite": "Unfavorite",
@@ -351,10 +389,10 @@
     "sortByFavoritesActive": "Undo sort by favorites"
   },
   "exploreDetail": {
-    "title": "Folder Details",
+    "title": "Deck Details",
     "createdBy": "Created by: {name}",
     "unknownUser": "Unknown User",
-    "totalPairs": "Total Pairs",
+    "totalCards": "Total Cards",
     "favorites": "Favorites",
     "createdAt": "Created At",
     "viewContent": "View Content",
@@ -385,11 +423,11 @@
     "memberSince": "Member Since",
     "joined": "Joined",
     "logout": "Logout",
-    "folders": {
-      "title": "Folders",
-      "noFolders": "No folders yet",
-      "folderName": "Folder Name",
-      "totalPairs": "Total Pairs",
+    "decks": {
+      "title": "Decks",
+      "noDecks": "No decks yet",
+      "deckName": "Deck Name",
+      "totalCards": "Total Cards",
       "createdAt": "Created At",
       "actions": "Actions",
       "view": "View"