feat: isolated cycle action — Check New Market Events

Décompose le cycle en 8 actions appelables individuellement.
Action 1 implémentée : scan de 4 sources (news RSS, surprises FRED,
MA crossovers yfinance, rapports institutionnels) → création de
market_events avec déduplication. UI CycleActions page + sidebar link.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/layout/Sidebar.tsx

@@ -1,7 +1,7 @@
 import { NavLink } from 'react-router-dom'
 import {
   LayoutDashboard, Globe, BarChart2, FlaskConical,
-  History, Calendar, TrendingUp, Zap, DollarSign, Settings, BrainCircuit, Activity, BookOpen, FileBarChart, Brain, ShieldAlert, Microscope, ScrollText, Gauge, GitCompare, Building2, Users, Layers, ScanEye, CandlestickChart, Crosshair
+  History, Calendar, TrendingUp, Zap, DollarSign, Settings, BrainCircuit, Activity, BookOpen, FileBarChart, Brain, ShieldAlert, Microscope, ScrollText, Gauge, GitCompare, Building2, Users, Layers, ScanEye, CandlestickChart, Crosshair, PlayCircle
 } from 'lucide-react'
 import { useGeoRiskScore, useAiStatus, usePortfolioSummary } from '../../hooks/useApi'
 import clsx from 'clsx'
@@ -29,6 +29,7 @@ const nav = [
   { to: '/specialist-desks', icon: Users, label: 'Specialist Desks' },
   { to: '/instruments', icon: CandlestickChart, label: 'Instrument Snap.' },
   { to: '/impact', icon: Crosshair, label: 'Impact Monitor' },
+  { to: '/cycle-actions', icon: PlayCircle, label: 'Cycle Actions' },
   { to: '/snapshot', icon: ScanEye, label: 'Snapshot Externe' },
   { to: '/timeline', icon: Layers, label: 'Timeline' },
   { to: '/logs', icon: ScrollText, label: 'System Logs' },