feat: eco desk enhanced config + EUR/USD causal simulator

Eco desk (market_event_detector.py + AIDesks.tsx):
- Add currencies filter (USD via FRED, EUR/GBP/JPY/etc via ff_calendar)
- Add min_impact filter (high / high+medium / all levels)
- Add create_market_event toggle — detect surprises without creating events
- Add lookback_releases — inject last N historical releases into event description
- New _check_ff_calendar_surprises() for non-USD surprising releases
- Frontend EcoConfig: currency chips, impact dropdown, releases input, toggle

EUR/USD Simulator (EuroSimulator.tsx):
- Pure frontend causal model — no API calls, no historical data
- 3-column layout: controls | causal chain SVG | results
- FED/BCE rate sliders + hawkish/dovish tone selector
- CPI/NFP/PMI surprise inputs
- SVG causal chain: CPI→CB→2Y→ΔRate→EURUSD with dynamic colors
- Real-time pip decomposition by factor, sensitivity bars
- Route /simulator + sidebar entry

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

frontend/src/App.tsx

@@ -29,6 +29,7 @@ import CycleActions from './pages/CycleActions'
 import MarketEvents from './pages/MarketEvents'
 import AIDesks from './pages/AIDesks'
 import MacroSeriesPage from './pages/MacroSeriesPage'
+import EuroSimulator from './pages/EuroSimulator'
 import { Navigate } from 'react-router-dom'
 import { useCycleWatcher } from './hooks/useApi'
 
@@ -78,6 +79,7 @@ export default function App() {
             <Route path="/market-events" element={<MarketEvents />} />
             <Route path="/cycle-actions" element={<CycleActions />} />
             <Route path="/ai-desks" element={<AIDesks />} />
+            <Route path="/simulator" element={<EuroSimulator />} />
           </Routes>
         </main>
       </div>