fix: add missing Agent exports in __init__.py

Export CompetitorAnalyzerAgent, MonitorAgent, SchemaAdvisorAgent
that were implemented but missing from the module's public API.

backend/app/agent_framework/agents/__init__.py

@@ -1,15 +1,21 @@
 """Agent 实现模块"""
 
 from .citation_detector import CitationDetectorAgent
+from .competitor_analyzer import CompetitorAnalyzerAgent
 from .content_generator_agent import ContentGeneratorAgent
 from .deai_agent import DeAIAgent
 from .geo_optimizer_agent import GEOOptimizerAgent
+from .monitor_agent import MonitorAgent
+from .schema_advisor import SchemaAdvisorAgent
 from .trend_agent import TrendAgent
 
 __all__ = [
     "CitationDetectorAgent",
+    "CompetitorAnalyzerAgent",
     "ContentGeneratorAgent",
     "DeAIAgent",
     "GEOOptimizerAgent",
+    "MonitorAgent",
+    "SchemaAdvisorAgent",
     "TrendAgent",
 ]