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/workspace.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-"""Workspace Manager - Create and manage agent workspaces."""
+"""Design-time workspace registry stored under `workspaces/`."""
 
 import logging
 from dataclasses import dataclass, field
@@ -323,5 +323,6 @@ class WorkspaceRegistry:
             yaml.safe_dump(config.to_dict(), f, allow_unicode=True, sort_keys=False)
 
 
-# Backward-compatible alias: legacy imports expect WorkspaceManager.
+# Backward-compatible alias: legacy imports expect WorkspaceManager to mean the
+# design-time `workspaces/` registry.
 WorkspaceManager = WorkspaceRegistry