feat: add Japanese language support, three-language subtitles for all demo scenes

public/demo/intro/intro_ja.vtt

@@ -0,0 +1,7 @@
+WEBVTT
+
+00:00.000 --> 00:02.000
+見知らぬ部屋で目覚めた
+
+00:02.500 --> 00:03.000
+目の前に二つのドアがある。選ばなければならない。

public/demo/investigation_site/investigation_en.vtt

@@ -0,0 +1,4 @@
+WEBVTT
+
+00:00.000 --> 00:05.000
+You step into a messy room, carefully looking around...

public/demo/investigation_site/investigation_ja.vtt

@@ -0,0 +1,4 @@
+WEBVTT
+
+00:00.000 --> 00:05.000
+散らかった部屋に入り、周りを注意深く観察する…

public/demo/left_door/left_door_ja.vtt

@@ -0,0 +1,7 @@
+WEBVTT
+
+00:00.000 --> 00:02.500
+光るドアを通り抜けると、明るい広間に出た
+
+00:02.500 --> 00:03.000
+見知らぬ人が手を差し伸べてきた

public/demo/stay/stay_ja.vtt

@@ -0,0 +1,4 @@
+WEBVTT
+
+00:00.000 --> 00:02.500
+その場に留まることを選んだ。時間がゆっくりと過ぎていく…

public/scenes/demo.json

@@ -67,7 +67,8 @@
       "subtitleUrl": "intro/intro.vtt",
       "subtitles": {
         "zh": "intro/intro.vtt",
-        "en": "intro/intro_en.vtt"
+        "en": "intro/intro_en.vtt",
+        "ja": "intro/intro_ja.vtt"
       },
       "bgmUrl": "shared/calm_bgm.mp3",
       "bgmVolume": 0.6,
@@ -108,6 +109,11 @@
       "videoUrl": "",
       "imageUrl": "investigation_site/investigation_scene.jpg",
       "subtitleUrl": "investigation_site/investigation.vtt",
+      "subtitles": {
+        "zh": "investigation_site/investigation.vtt",
+        "en": "investigation_site/investigation_en.vtt",
+        "ja": "investigation_site/investigation_ja.vtt"
+      },
       "hotspots": [
         {
           "id": "hs_desk",
@@ -175,6 +181,11 @@
       "id": "left_door",
       "videoUrl": "left_door/left_door.mp4",
       "subtitleUrl": "left_door/left_door.vtt",
+      "subtitles": {
+        "zh": "left_door/left_door.vtt",
+        "en": "left_door/left_door_en.vtt",
+        "ja": "left_door/left_door_ja.vtt"
+      },
       "choices": [
         {
           "text": "与陌生人握手",
@@ -261,6 +272,11 @@
       "id": "stay",
       "videoUrl": "stay/stay_loop.mp4",
       "subtitleUrl": "stay/stay.vtt",
+      "subtitles": {
+        "zh": "stay/stay.vtt",
+        "en": "stay/stay_en.vtt",
+        "ja": "stay/stay_ja.vtt"
+      },
       "bgmUrl": "shared/calm_bgm.mp3",
       "bgmVolume": 0.6,
       "videoMuted": true,

src/components/LangSwitch.vue

@@ -14,6 +14,10 @@ const { currentLang, setLang, t } = useI18n()
       :class="['lang-btn', { active: currentLang === 'en' }]"
       @click="setLang('en')"
     >English</button>
+    <button
+      :class="['lang-btn', { active: currentLang === 'ja' }]"
+      @click="setLang('ja')"
+    >日本語</button>
   </div>
 </template>
 
@@ -29,6 +33,7 @@ const { currentLang, setLang, t } = useI18n()
   color: #888;
   background: rgba(255, 255, 255, 0.05);
   border: 1px solid rgba(255, 255, 255, 0.1);
+  border-radius: 0;
   cursor: pointer;
   transition: all 0.15s;
 }

src/composables/useI18n.ts

@@ -1,9 +1,10 @@
 import { ref } from 'vue'
 import zh from '@/locales/zh.json'
 import en from '@/locales/en.json'
+import ja from '@/locales/ja.json'
 
-const messages = { zh, en } as const
-type Lang = 'zh' | 'en'
+const messages = { zh, en, ja } as const
+type Lang = 'zh' | 'en' | 'ja'
 
 const currentLang = ref<Lang>(
   (localStorage.getItem('lang') as Lang) || 'zh'

src/locales/ja.json

@@ -0,0 +1,79 @@
+{
+  "ui": {
+    "start": "はじめる",
+    "resume": "つづきから",
+    "chapters": "チャプター",
+    "menu": "メニュー",
+    "save": "セーブ",
+    "load": "ロード",
+    "close": "とじる",
+    "skip": "スキップ",
+    "fullscreen": "フルスクリーン",
+    "exitFullscreen": "フルスクリーン解除",
+    "gameEnd": "おわり",
+    "choose": "選んでください",
+    "back": "もどる",
+    "autoSave": "オートセーブ",
+    "empty": "なし",
+    "loading": "読み込み中...",
+    "speed": "倍速",
+    "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"
+  },
+  "scene": {
+    "intro": {
+      "choice": {
+        "left_door": "左にある光るドアへ向かう",
+        "right_door": "右にある普通のドアへ向かう",
+        "search": "部屋を念入りに調べる",
+        "stay": "その場に留まる"
+      }
+    },
+    "left_door": {
+      "choice": {
+        "handshake": "見知らぬ人と握手する",
+        "reject": "握手を断り、警戒を続ける"
+      }
+    },
+    "right_door": {
+      "choice": {
+        "continue": "先へ進む",
+        "back": "引き返す"
+      }
+    },
+    "trust_ending": {
+      "choice": {
+        "journey": "信頼の旅に出る（trust >= 80 が必要）",
+        "leave": "ここを去る"
+      }
+    },
+    "investigation_site": {
+      "choice": {
+        "leave": "部屋を出る"
+      }
+    },
+    "desk_detail": {
+      "choice": {
+        "return": "調査現場に戻る",
+        "leave": "立ち去る"
+      }
+    },
+    "stay": {
+      "choice": {
+        "stand": "立ち上がって去る"
+      }
+    },
+    "qte_success": {
+      "choice": {
+        "continue": "先へ進む",
+        "back": "引き返す"
+      }
+    },
+    "qte_fail": {
+      "choice": {
+        "continue": "先へ進む",
+        "back": "引き返す"
+      }
+    }
+  }
+}