Phase 5: Agent grouping and selection after Step 2

Backend:
- Add /api/agent-group/categorize endpoint — AI groups agents by role
- Add /api/agent-group/filter endpoint — filter by selected groups
- Groups with default_enabled=false (advertiser, brand) are unchecked

Frontend:
- Add agent groups section in Step2EnvSetup.vue
- 'Auto-categorize' button triggers AI grouping
- Show groups with checkboxes (enabled groups checked, disabled unchecked)
- Auto-remove unchecked agents when proceeding to Step 3
- Show selected count summary

backend/app/__init__.py

@@ -65,10 +65,12 @@ def create_app(config_class=Config):
     # 注册蓝图
     from .api import graph_bp, simulation_bp, report_bp
     from .api.template import template_bp
+    from .api.agent_group import agent_group_bp
     app.register_blueprint(graph_bp, url_prefix='/api/graph')
     app.register_blueprint(simulation_bp, url_prefix='/api/simulation')
     app.register_blueprint(report_bp, url_prefix='/api/report')
     app.register_blueprint(template_bp, url_prefix='/api/template')
+    app.register_blueprint(agent_group_bp, url_prefix='/api/agent-group')
     
     # 健康检查
     @app.route('/health')