feat: open catalogue + book pages to public (hybrid open model)

Reading content is now publicly accessible without login:
- /catalogue, /books/[slug], /books/[slug]/chapters, /books/[slug]/chapters/[n]
  are all public — no login redirect
- /books (personal library), /profile, /admin remain protected

Unauthenticated UX:
- Chapter page: "Audio narration available — Sign in to listen" banner
  replaces the audio player for logged-out visitors
- Book detail: bookmark icon links to /login instead of triggering
  the save action (both desktop and mobile CTAs)

SEO:
- robots.txt updated: Allow /books/ and /catalogue, Disallow /books (library)
- sitemap.xml now includes /catalogue as primary crawl entry point

i18n: added reader_signin_for_audio, reader_signin_audio_desc,
      book_detail_signin_to_save in all 5 languages

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/messages/en.json

@@ -48,6 +48,7 @@
   "player_play": "Play",
   "player_pause": "Pause",
   "player_speed_label": "Playback speed {speed}x",
+  "player_seek_label": "Chapter progress",
   "player_change_speed": "Change playback speed",
   "player_auto_next_on": "Auto-next on",
   "player_auto_next_off": "Auto-next off",
@@ -99,6 +100,7 @@
   "catalogue_results_count": "{n} results",
 
   "book_detail_page_title": "{title} — libnovel",
+  "book_detail_signin_to_save": "Sign in to save",
   "book_detail_add_to_library": "Add to Library",
   "book_detail_remove_from_library": "Remove from Library",
   "book_detail_read_now": "Read Now",
@@ -123,6 +125,8 @@
   "reader_page_title": "{title} — Ch.{n} — libnovel",
   "reader_play_narration": "Play narration",
   "reader_generating_audio": "Generating audio…",
+  "reader_signin_for_audio": "Audio narration available",
+  "reader_signin_audio_desc": "Sign in to listen to this chapter narrated by AI.",
   "reader_audio_error": "Audio generation failed.",
   "reader_prev_chapter": "Previous chapter",
   "reader_next_chapter": "Next chapter",

ui/messages/fr.json

@@ -48,6 +48,7 @@
   "player_play": "Lecture",
   "player_pause": "Pause",
   "player_speed_label": "Vitesse {speed}x",
+  "player_seek_label": "Progression du chapitre",
   "player_change_speed": "Changer la vitesse",
   "player_auto_next_on": "Suivant auto activé",
   "player_auto_next_off": "Suivant auto désactivé",
@@ -99,6 +100,7 @@
   "catalogue_results_count": "{n} résultats",
 
   "book_detail_page_title": "{title} — libnovel",
+  "book_detail_signin_to_save": "Connectez-vous pour sauvegarder",
   "book_detail_add_to_library": "Ajouter à la bibliothèque",
   "book_detail_remove_from_library": "Retirer de la bibliothèque",
   "book_detail_read_now": "Lire maintenant",
@@ -123,6 +125,8 @@
   "reader_page_title": "{title} — Ch.{n} — libnovel",
   "reader_play_narration": "Lire la narration",
   "reader_generating_audio": "Génération audio…",
+  "reader_signin_for_audio": "Narration audio disponible",
+  "reader_signin_audio_desc": "Connectez-vous pour écouter ce chapitre narré par l'IA.",
   "reader_audio_error": "Échec de la génération audio.",
   "reader_prev_chapter": "Chapitre précédent",
   "reader_next_chapter": "Chapitre suivant",

ui/messages/id.json

@@ -48,6 +48,7 @@
   "player_play": "Putar",
   "player_pause": "Jeda",
   "player_speed_label": "Kecepatan {speed}x",
+  "player_seek_label": "Kemajuan bab",
   "player_change_speed": "Ubah kecepatan",
   "player_auto_next_on": "Auto-lanjut aktif",
   "player_auto_next_off": "Auto-lanjut nonaktif",
@@ -99,6 +100,7 @@
   "catalogue_results_count": "{n} hasil",
 
   "book_detail_page_title": "{title} — libnovel",
+  "book_detail_signin_to_save": "Masuk untuk menyimpan",
   "book_detail_add_to_library": "Tambah ke Perpustakaan",
   "book_detail_remove_from_library": "Hapus dari Perpustakaan",
   "book_detail_read_now": "Baca Sekarang",
@@ -123,6 +125,8 @@
   "reader_page_title": "{title} — Bab.{n} — libnovel",
   "reader_play_narration": "Putar narasi",
   "reader_generating_audio": "Membuat audio…",
+  "reader_signin_for_audio": "Narasi audio tersedia",
+  "reader_signin_audio_desc": "Masuk untuk mendengarkan bab ini yang dinarasikan oleh AI.",
   "reader_audio_error": "Pembuatan audio gagal.",
   "reader_prev_chapter": "Bab sebelumnya",
   "reader_next_chapter": "Bab berikutnya",

ui/messages/pt-BR.json

@@ -48,6 +48,7 @@
   "player_play": "Reproduzir",
   "player_pause": "Pausar",
   "player_speed_label": "Velocidade {speed}x",
+  "player_seek_label": "Progresso do capítulo",
   "player_change_speed": "Mudar velocidade",
   "player_auto_next_on": "Próximo automático ativado",
   "player_auto_next_off": "Próximo automático desativado",
@@ -99,6 +100,7 @@
   "catalogue_results_count": "{n} resultados",
 
   "book_detail_page_title": "{title} — libnovel",
+  "book_detail_signin_to_save": "Entre para salvar",
   "book_detail_add_to_library": "Adicionar à Biblioteca",
   "book_detail_remove_from_library": "Remover da Biblioteca",
   "book_detail_read_now": "Ler Agora",
@@ -123,6 +125,8 @@
   "reader_page_title": "{title} — Cap.{n} — libnovel",
   "reader_play_narration": "Reproduzir narração",
   "reader_generating_audio": "Gerando áudio…",
+  "reader_signin_for_audio": "Narração de áudio disponível",
+  "reader_signin_audio_desc": "Entre para ouvir este capítulo narrado por IA.",
   "reader_audio_error": "Falha na geração de áudio.",
   "reader_prev_chapter": "Capítulo anterior",
   "reader_next_chapter": "Próximo capítulo",

ui/messages/ru.json

@@ -48,6 +48,7 @@
   "player_play": "Воспроизвести",
   "player_pause": "Пауза",
   "player_speed_label": "Скорость {speed}x",
+  "player_seek_label": "Прогресс главы",
   "player_change_speed": "Изменить скорость",
   "player_auto_next_on": "Автопереход вкл.",
   "player_auto_next_off": "Автопереход выкл.",
@@ -99,6 +100,7 @@
   "catalogue_results_count": "{n} результатов",
 
   "book_detail_page_title": "{title} — libnovel",
+  "book_detail_signin_to_save": "Войдите, чтобы сохранить",
   "book_detail_add_to_library": "В библиотеку",
   "book_detail_remove_from_library": "Удалить из библиотеки",
   "book_detail_read_now": "Читать",
@@ -123,6 +125,8 @@
   "reader_page_title": "{title} — Гл.{n} — libnovel",
   "reader_play_narration": "Воспроизвести озвучку",
   "reader_generating_audio": "Генерация аудио…",
+  "reader_signin_for_audio": "Доступна аудионарративация",
+  "reader_signin_audio_desc": "Войдите, чтобы слушать эту главу в озвучке ИИ.",
   "reader_audio_error": "Ошибка генерации аудио.",
   "reader_prev_chapter": "Предыдущая глава",
   "reader_next_chapter": "Следующая глава",