feat: i18n system, lang switch component, english subtitles, UI improvements, roadmap update

public/scenes/demo.json

@@ -33,6 +33,10 @@
       "id": "intro",
       "videoUrl": "/videos/intro.mp4",
       "subtitleUrl": "/subtitles/intro.vtt",
+      "subtitles": {
+        "zh": "/subtitles/intro.vtt",
+        "en": "/subtitles/intro_en.vtt"
+      },
       "bgmUrl": "/audio/calm_bgm.mp3",
       "bgmVolume": 0.6,
       "bgmCrossFade": 1.5,
@@ -40,6 +44,7 @@
       "choices": [
         {
           "text": "走向左边那扇发光的门",
+          "textKey": "scene.intro.choice.left_door",
           "targetScene": "left_door",
           "effects": [
             { "type": "add", "target": "courage", "value": 10 }
@@ -47,6 +52,7 @@
         },
         {
           "text": "走向右边那扇普通的门",
+          "textKey": "scene.intro.choice.right_door",
           "targetScene": "right_door",
           "effects": [
             { "type": "add", "target": "courage", "value": -5 }
@@ -54,10 +60,12 @@
         },
         {
           "text": "仔细搜索房间",
+          "textKey": "scene.intro.choice.search",
           "targetScene": "investigation_site"
         },
         {
           "text": "留在原地，什么也不做",
+          "textKey": "scene.intro.choice.stay",
           "targetScene": "stay"
         }
       ]