chore: 项目更名为 HuiBrain

全局替换 EduBrain -> HuiBrain, edu-brain -> huibrain, edu_brain -> hui_brain, EDUBRAIN -> HUIBRAIN
涉及文件：README.md, pyproject.toml, docker-compose.yml, .env, .env.example,
app/config.py, app/main.py, app/wework_bot.py, app/__init__.py, app/mcp/server.py,
static/index.html, docs/IMAGE_API_GUIDE.md

docker-compose.yml

@@ -5,7 +5,7 @@ services:
     build:
       context: .
       dockerfile: Dockerfile
-    container_name: edu-brain-app
+    container_name: huibrain-app
     restart: unless-stopped
     ports:
       - "${APP_PORT:-8000}:8000"