refactor(cleanup): remove legacy agent classes and complete EvoAgent migration

Remove deprecated AnalystAgent, PMAgent, and RiskAgent classes.
All agent creation now goes through UnifiedAgentFactory creating EvoAgent instances.

- Delete backend/agents/analyst.py (169 lines)
- Delete backend/agents/portfolio_manager.py (420 lines)
- Delete backend/agents/risk_manager.py (139 lines)
- Update all imports to use EvoAgent exclusively
- Clean up unused imports across 25 files
- Update tests to work with simplified agent structure

Constraint: EvoAgent is now the single source of truth for all agent roles
Constraint: UnifiedAgentFactory handles runtime agent creation
Rejected: Keep legacy aliases | creates maintenance burden
Confidence: high
Scope-risk: moderate (affects agent instantiation paths)
Directive: All new agent features must be added to EvoAgent, not legacy classes
Not-tested: Kubernetes sandbox executor (marked with TODO)

backend/core/pipeline.py

@@ -26,7 +26,7 @@ from backend.agents.team_pipeline_config import (
     resolve_active_analysts,
     update_active_analysts,
 )
-from backend.agents import AnalystAgent, EvoAgent
+from backend.agents import EvoAgent
 from backend.agents.agent_workspace import load_agent_workspace_config
 from backend.agents.toolkit_factory import create_agent_toolkit
 from backend.agents.workspace_manager import WorkspaceManager
@@ -1586,46 +1586,30 @@ class TradingPipeline:
             ),
         )
 
-        # Determine whether to use EvoAgent based on EVO_AGENT_IDS
-        use_evo_agent = analyst_type in _resolve_evo_agent_ids()
-
-        if use_evo_agent:
-            from backend.agents.skills_manager import SkillsManager
-            skills_manager = SkillsManager(project_root=project_root)
-            workspace_dir = skills_manager.get_agent_asset_dir(
-                config_name,
-                agent_id,
-            )
-            agent_config = load_agent_workspace_config(workspace_dir / "agent.yaml")
-            agent = EvoAgent(
-                agent_id=agent_id,
-                config_name=config_name,
-                workspace_dir=workspace_dir,
-                model=get_agent_model(analyst_type),
-                formatter=get_agent_formatter(analyst_type),
-                prompt_files=agent_config.prompt_files,
-            )
-            agent.toolkit = create_agent_toolkit(
-                agent_id=agent_id,
-                config_name=config_name,
-                active_skill_dirs=[],
-            )
-            setattr(agent, "run_id", config_name)
-            # Keep workspace_id for backward compatibility
-            setattr(agent, "workspace_id", config_name)
-        else:
-            agent = AnalystAgent(
-                analyst_type=analyst_type,
-                toolkit=create_agent_toolkit(
-                    agent_id=agent_id,
-                    config_name=config_name,
-                    active_skill_dirs=[],
-                ),
-                model=get_agent_model(analyst_type),
-                formatter=get_agent_formatter(analyst_type),
-                agent_id=agent_id,
-                config={"config_name": config_name},
-            )
+        # Create EvoAgent with workspace-driven configuration
+        from backend.agents.skills_manager import SkillsManager
+        skills_manager = SkillsManager(project_root=project_root)
+        workspace_dir = skills_manager.get_agent_asset_dir(
+            config_name,
+            agent_id,
+        )
+        agent_config = load_agent_workspace_config(workspace_dir / "agent.yaml")
+        agent = EvoAgent(
+            agent_id=agent_id,
+            config_name=config_name,
+            workspace_dir=workspace_dir,
+            model=get_agent_model(analyst_type),
+            formatter=get_agent_formatter(analyst_type),
+            prompt_files=agent_config.prompt_files,
+        )
+        agent.toolkit = create_agent_toolkit(
+            agent_id=agent_id,
+            config_name=config_name,
+            active_skill_dirs=[],
+        )
+        setattr(agent, "run_id", config_name)
+        # Keep workspace_id for backward compatibility
+        setattr(agent, "workspace_id", config_name)
         self._dynamic_analysts[agent_id] = agent
         update_active_analysts(
             project_root=project_root,