feat: i18n StoryGallery UI labels and data layer chapter/ending names

src/locales/en.json

@@ -26,6 +26,7 @@
     "achievements": "Achievements",
     "gallery": "Gallery",
     "story": "Story Progress",
+    "startChapter": "Start",
     "noAutoSave": "No auto save yet",
     "autoSaveHint": "Game auto-saves to slot 0 at each scene change",
     "language": "Language",

src/locales/ja.json

@@ -25,6 +25,8 @@
     "pauseHint": "Esc = 再開",
     "achievements": "実績",
     "gallery": "ギャラリー",
+    "story": "ストーリー進行",
+    "startChapter": "開始",
     "noAutoSave": "オートセーブがありません",
     "autoSaveHint": "シーン切替時にスロット0に自動保存されます",
     "language": "言語",

src/locales/zh.json

@@ -26,6 +26,7 @@
     "achievements": "成就",
     "gallery": "画廊",
     "story": "故事进度",
+    "startChapter": "开始",
     "noAutoSave": "暂无自动存档",
     "autoSaveHint": "游戏会在每次场景切换时自动保存到槽位 0",
     "language": "语言",