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/tests/test_news_service_app.py

@@ -178,3 +178,84 @@ def test_news_service_range_explain(monkeypatch):
 
     assert response.status_code == 200
     assert response.json()["result"]["news_count"] == 1
+
+
+def test_news_service_contract_stability():
+    """Verify news service API maintains contract stability."""
+    app = create_app()
+    routes = {route.path: route for route in app.routes if hasattr(route, "methods")}
+
+    # Health endpoint
+    assert "/health" in routes
+
+    # News/explain endpoints
+    assert "/api/enriched-news" in routes
+    assert "/api/news-for-date" in routes
+    assert "/api/news-timeline" in routes
+    assert "/api/categories" in routes
+    assert "/api/similar-days" in routes
+    assert "/api/stories/{ticker}" in routes
+    assert "/api/range-explain" in routes
+
+    # Verify all are GET endpoints (read-only service)
+    for path in ["/api/enriched-news", "/api/news-for-date", "/api/news-timeline",
+                 "/api/categories", "/api/similar-days", "/api/stories/{ticker}",
+                 "/api/range-explain"]:
+        assert "GET" in routes[path].methods
+
+
+def test_news_service_enriched_news_contract(monkeypatch):
+    """Test enriched news endpoint maintains response contract."""
+    app = create_app()
+    app.dependency_overrides.clear()
+    from backend.apps import news_service as news_service_module
+
+    app.dependency_overrides[news_service_module.get_market_store] = lambda: _FakeStore()
+    monkeypatch.setattr(
+        "backend.domains.news.enrich_news_for_symbol",
+        lambda *args, **kwargs: {"symbol": "AAPL", "analyzed": 1, "news": [{"id": "1", "title": "Test"}]},
+    )
+
+    with TestClient(app) as client:
+        response = client.get(
+            "/api/enriched-news",
+            params={"ticker": "AAPL", "end_date": "2026-03-23"},
+        )
+
+    assert response.status_code == 200
+    payload = response.json()
+    assert "news" in payload
+
+
+def test_news_service_stories_contract(monkeypatch):
+    """Test stories endpoint maintains response contract."""
+    app = create_app()
+    from backend.apps import news_service as news_service_module
+
+    app.dependency_overrides[news_service_module.get_market_store] = lambda: _FakeStore()
+    monkeypatch.setattr(
+        "backend.domains.news.enrich_news_for_symbol",
+        lambda *args, **kwargs: {"symbol": "AAPL", "analyzed": 1},
+    )
+    monkeypatch.setattr(
+        "backend.domains.news.get_or_create_stock_story",
+        lambda store, symbol, as_of_date: {
+            "symbol": symbol,
+            "as_of_date": as_of_date,
+            "story": "story body",
+            "source": "local",
+            "headline": "Test Headline",
+        },
+    )
+
+    with TestClient(app) as client:
+        response = client.get(
+            "/api/stories/AAPL",
+            params={"as_of_date": "2026-03-23"},
+        )
+
+    assert response.status_code == 200
+    payload = response.json()
+    assert "symbol" in payload
+    assert "as_of_date" in payload
+    assert "story" in payload