feat: restructure menu and add file import

- Consolidate "Add word" menu with submenu (Manual, Thematic, Import)
- Add file import support (.txt, .md) with AI batch translation
- Add vocabulary pagination with navigation buttons
- Add "Add word" button in tasks for new words mode
- Fix undefined variables bug in vocabulary confirm handler
- Add localization keys for add_menu in ru/en/ja

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

locales/en.json

@@ -5,15 +5,32 @@
     "task": "🧠 Task",
     "practice": "💬 Practice",
     "words": "🎯 Thematic words",
-    "import": "📖 Import from text",
+    "import": "📖 Import",
     "stats": "📊 Stats",
     "settings": "⚙️ Settings",
     "below": "Main menu below ⤵️"
   },
+  "add_menu": {
+    "title": "➕ <b>Add words</b>\n\nChoose method:",
+    "manual": "📝 Manual",
+    "thematic": "🎯 Thematic words",
+    "import": "📖 Import"
+  },
+  "import_menu": {
+    "title": "📖 <b>Import words</b>\n\nChoose import method:",
+    "from_text": "📝 From text",
+    "from_file": "📄 From file (.txt, .md)",
+    "file_hint": "📄 <b>Import from file</b>\n\nSend a .txt or .md file with your words.\n\n<b>Formats:</b>\n• One word per line (AI will translate)\n• <code>word - translation</code>\n• <code>word : translation</code>"
+  },
   "common": {
     "start_first": "First run /start to register",
     "translation": "Translation"
   },
+  "lang": {
+    "ru": "Russian",
+    "en": "English",
+    "ja": "Japanese"
+  },
   "import": {
     "title": "📖 <b>Import words from text</b>",
     "desc": "Send me text in your learning language, and I will extract useful words to study.",
@@ -56,7 +73,9 @@
     "header": "<b>📚 Your vocabulary:</b>",
     "accuracy_inline": "({n}% accuracy)",
     "shown_last": "<i>Showing last 10 of {n} words</i>",
-    "total": "<i>Total words: {n}</i>"
+    "total": "<i>Total words: {n}</i>",
+    "page_info": "\n📖 Page {page} of {total} • Total words: {count}",
+    "close_btn": "❌ Close"
   },
   "practice": {
     "start_text": "💬 <b>Dialogue practice with AI</b>\n\nChoose a scenario:\n\n• AI will play a role\n• You can chat in English\n• AI will correct your mistakes\n• Use /stop to finish\n\nPick a scenario:",
@@ -92,6 +111,12 @@
     "go_words_hint": "Use /words [topic] for word sets"
   },
   "tasks": {
+    "choose_mode": "🧠 <b>Choose task mode:</b>",
+    "mode_vocabulary": "📚 Words from vocabulary",
+    "mode_new_words": "✨ New words",
+    "generating_new": "🔄 Generating new words...",
+    "generate_failed": "❌ Failed to generate words. Try again later.",
+    "translate_to": "Translate to {lang_name}",
     "no_words": "📚 You don't have words to practice yet!\n\nAdd some words with /add and come back.",
     "stopped": "Exercises stopped. Use /task to start again.",
     "finished": "Exercises finished. Use /task to start again.",
@@ -104,6 +129,9 @@
     "right_answer": "Right answer",
     "next_btn": "➡️ Next task",
     "stop_btn": "🔚 Stop",
+    "add_word_btn": "➕ Add word",
+    "word_added": "✅ Word '{word}' added to vocabulary!",
+    "word_already_exists": "Word '{word}' is already in vocabulary",
     "cancelled": "Cancelled. You can return to tasks with /task.",
     "finish_title": "{emoji} <b>Task finished!</b>",
     "correct_of": "Correct answers: <b>{correct}</b> of {total}",
@@ -219,6 +247,18 @@
   "import_extra": {
     "cancelled": "❌ Import cancelled."
   },
+  "import_file": {
+    "unsupported_format": "❌ Unsupported file format.\n\nSupported: .txt, .md\n\nFile format:\n<code>word - translation</code>\n<code>word : translation</code>",
+    "too_large": "❌ File is too large (max 1 MB)",
+    "encoding_error": "❌ Encoding error. Make sure the file is UTF-8",
+    "download_error": "❌ Failed to download file. Try again",
+    "no_words_found": "❌ No words found in file.\n\nMake sure the format is correct:\n<code>word - translation</code>\n<code>word : translation</code>",
+    "truncated": "⚠️ File contains more than {n} words. Importing first {n}.",
+    "found_header": "📄 <b>Words found in file: {n}</b>",
+    "choose_action": "Choose action:",
+    "add_all_btn": "✅ Add all ({n})",
+    "translating": "🔄 Translating words with AI..."
+  },
   "level_test_extra": {
     "generating": "🔄 Generating questions...",
     "generate_failed": "❌ Failed to generate test. Try later or use /settings to set level manually.",