feat: Instrument Snapshot Dashboard — 5-layer synchronized view for 20 instruments

- 20 instruments configured (equity indices, metals, energy, bonds, FX, stocks, crypto)
  each with custom drivers, regime labels, MA periods, event keywords, ai_context
- InstrumentChart: TradingView lightweight-charts candlesticks + MA lines + Bollinger
  + volume histogram + macro event markers overlaid on price
- InstrumentDashboard: regime detection card (scores + signals), trend indicators
  (RSI gauge, MA slopes, momentum, 52W range), events card (links to Timeline),
  AI narrative via GPT-4o-mini (cached by day)
- Backend: instrument_service (OHLCV fetch, indicators, regime scoring, GPT narrative)
  + /api/instruments router (3 endpoints)
- Route: /instruments/:id with selector dropdown, period buttons (3M/6M/1Y/2Y/5Y)

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
+  History, Calendar, TrendingUp, Zap, DollarSign, Settings, BrainCircuit, Activity, BookOpen, FileBarChart, Brain, ShieldAlert, Microscope, ScrollText, Gauge, GitCompare, Building2, Users, Layers, ScanEye, CandlestickChart
 } from 'lucide-react'
 import { useGeoRiskScore, useAiStatus, usePortfolioSummary } from '../../hooks/useApi'
 import clsx from 'clsx'
@@ -27,6 +27,7 @@ const nav = [
   { to: '/calendar', icon: Calendar, label: 'Calendar' },
   { to: '/institutional', icon: Building2, label: 'Inst. Reports' },
   { to: '/specialist-desks', icon: Users, label: 'Specialist Desks' },
+  { to: '/instruments', icon: CandlestickChart, label: 'Instrument Snap.' },
   { to: '/snapshot', icon: ScanEye, label: 'Snapshot Externe' },
   { to: '/timeline', icon: Layers, label: 'Timeline' },
   { to: '/logs', icon: ScrollText, label: 'System Logs' },