feat(agent): complete EvoAgent integration for all 6 agent roles

Migrate all agent roles from Legacy to EvoAgent architecture:
- fundamentals_analyst, technical_analyst, sentiment_analyst, valuation_analyst
- risk_manager, portfolio_manager

Key changes:
- EvoAgent now supports Portfolio Manager compatibility methods (_make_decision,
  get_decisions, get_portfolio_state, load_portfolio_state, update_portfolio)
- Add UnifiedAgentFactory for centralized agent creation
- ToolGuard with batch approval API and WebSocket broadcast
- Legacy agents marked deprecated (AnalystAgent, RiskAgent, PMAgent)
- Remove backend/agents/compat.py migration shim
- Add run_id alongside workspace_id for semantic clarity
- Complete integration test coverage (13 tests)
- All smoke tests passing for 6 agent roles

Constraint: Must maintain backward compatibility with existing run configs
Constraint: Memory support must work with EvoAgent (no fallback to Legacy)
Rejected: Separate PM implementation for EvoAgent | unified approach cleaner
Confidence: high
Scope-risk: broad
Directive: EVO_AGENT_IDS env var still respected but defaults to all roles
Not-tested: Kubernetes sandbox mode for skill execution

backend/agents/__init__.py

@@ -1,14 +1,14 @@
 # -*- coding: utf-8 -*-
 """
-Agents package - EvoAgent architecture for trading system.
+Agents package for the current mixed runtime.
 
 Exports:
 - EvoAgent: Next-generation agent with workspace support
 - ToolGuardMixin: Tool call approval/denial flow
 - CommandHandler: System command handling
-- AgentFactory: Dynamic agent creation and management
-- WorkspaceManager: Legacy name for the persistent workspace registry
-- WorkspaceRegistry: Explicit run-time-agnostic workspace registry
+- AgentFactory: Design-time agent creation under `workspaces/`
+- WorkspaceManager: Legacy alias for the persistent `workspaces/` registry
+- WorkspaceRegistry: Explicit design-time `workspaces/` registry
 - RunWorkspaceManager: Run-scoped workspace asset manager
 - AgentRegistry: Central agent registry
 - Legacy compatibility: AnalystAgent, PMAgent, RiskAgent
@@ -26,9 +26,6 @@ from .analyst import AnalystAgent
 from .portfolio_manager import PMAgent
 from .risk_manager import RiskAgent
 
-# Compatibility layer
-from .compat import LegacyAgentAdapter, adapt_agent, adapt_agents, is_legacy_agent
-
 __all__ = [
     # New architecture
     "EvoAgent",
@@ -48,9 +45,4 @@ __all__ = [
     "AnalystAgent",
     "PMAgent",
     "RiskAgent",
-    # Compatibility layer
-    "LegacyAgentAdapter",
-    "adapt_agent",
-    "adapt_agents",
-    "is_legacy_agent",
 ]