docs: 重构文档结构，添加独立模块区域 (#349)

* docs: 重构文档结构，添加独立模块区域

- 新增 /modules/ 目录用于功能模块文档
- 移动 behavior-tree 从 /guide/ 到 /modules/
- 添加模块总览页面
- 更新导航栏添加"模块"入口
- 更新侧边栏：模块区域独立侧边栏
- 更新 i18n 配置支持新模块

* style(docs): 提高文字对比度

docs/.vitepress/i18n/en.json

@@ -3,6 +3,7 @@
     "home": "Home",
     "quickStart": "Quick Start",
     "guide": "Guide",
+    "modules": "Modules",
     "api": "API",
     "examples": "Examples",
     "workerDemo": "Worker System Demo",
@@ -54,7 +55,26 @@
     "utilities": "Utilities",
     "interfaces": "Interfaces",
     "decorators": "Decorators",
-    "enums": "Enums"
+    "enums": "Enums",
+    "modulesOverview": "Modules Overview",
+    "aiModules": "AI Modules",
+    "gameplayModules": "Gameplay",
+    "toolModules": "Tools",
+    "networkModules": "Network",
+    "fsm": "State Machine (FSM)",
+    "fsmOverview": "Overview",
+    "timer": "Timer System",
+    "timerOverview": "Overview",
+    "spatial": "Spatial Index",
+    "spatialOverview": "Overview",
+    "pathfinding": "Pathfinding",
+    "pathfindingOverview": "Overview",
+    "blueprint": "Visual Scripting",
+    "blueprintOverview": "Overview",
+    "procgen": "Procedural Generation",
+    "procgenOverview": "Overview",
+    "network": "Network Sync",
+    "networkOverview": "Overview"
   },
   "home": {
     "title": "ESEngine - High-performance TypeScript ECS Framework",