feat: institutional reports — CFTC COT + EIA petroleum weekly

- New institutional_reports table (DB) with importance, signals per asset class, key points, absorption tracking
- cot_fetcher.py: CFTC Socrata API (6dca-aqww), 7 instruments (Gold/Silver/Copper/WTI/NatGas/SP500/EURUSD), net positioning + 52-week z-score
- eia_fetcher.py: EIA API v2, 4 series (crude/Cushing/gasoline/distillates), WoW surprise detection
- institutional.py router: GET /reports, GET /reports/{id}, POST /refresh, GET /stats
- institutional_scheduler.py: weekly auto-fetch (COT Saturdays, EIA Wednesday afternoons)
- ai_analyzer.py: build_institutional_block() + institutional_block param injected into AI scoring prompt
- auto_cycle.py: inject institutional block into suggestion + scoring, absorption tracking via keyword overlap after each cycle commentary
- InstitutionalReports.tsx: full page with filter bar (type/category/importance/period), cards with key point bullets, EXTREME alerts highlighted, signal badges, absorption badge, trading implications, expandable detail

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
+  History, Calendar, TrendingUp, Zap, DollarSign, Settings, BrainCircuit, Activity, BookOpen, FileBarChart, Brain, ShieldAlert, Microscope, ScrollText, Gauge, GitCompare, Building2
 } from 'lucide-react'
 import { useGeoRiskScore, useAiStatus, usePortfolioSummary } from '../../hooks/useApi'
 import clsx from 'clsx'
@@ -24,6 +24,7 @@ const nav = [
   { to: '/position-history', icon: GitCompare, label: 'Position History' },
   { to: '/backtest', icon: History, label: 'Backtest' },
   { to: '/calendar', icon: Calendar, label: 'Calendar' },
+  { to: '/institutional', icon: Building2, label: 'Inst. Reports' },
   { to: '/logs', icon: ScrollText, label: 'System Logs' },
   { to: '/config', icon: Settings, label: 'Configuration' },
 ]