feat: market events db migration + generation date filter

Database migration:
- Add 'origin' and 'source_refs' columns to market_events ALTER TABLE migration
  (sub_type/actual_value/expected_value/surprise_pct were already there)
- All new tables (macro_gauge_snapshots, ai_desks) created via CREATE TABLE IF NOT EXISTS
  on next init_db() call (container restart)

Backend:
- GET /api/market-events/db-status — health check returning row counts,
  latest dates, and missing columns for all 6 tables needed by the detector
- list_events() now accepts gen_date_from / gen_date_to query params
  filtering by date(created_at) — separate from start_date event date filters

Frontend (MarketEvents.tsx):
- MarketEvent interface: add created_at field
- EventRow: show generation date as ⚡MM-DD next to event date
- Extended filters: new '⚡ Date de génération' section with from/to inputs
  filtered independently from the event date range
- Clear-all button includes genFrom/genTo reset

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

frontend/src/pages/MarketEvents.tsx

@@ -45,6 +45,7 @@ interface MarketEvent {
   absorption_pct: number | null
   source_refs: SourceRef[]
   origin?: string
+  created_at?: string
   impacts?: InstrumentImpact[]
   evaluated?: boolean
 }
@@ -780,6 +781,11 @@ function EventRow({
               {(ORIGIN_META[ev.origin] ?? ORIGIN_META['unknown']).icon}
             </span>
           )}
+          {ev.created_at && (
+            <span className="text-[10px] text-slate-700 shrink-0" title={`Généré le ${ev.created_at}`}>
+              ⚡{ev.created_at.slice(5, 10)}
+            </span>
+          )}
         </div>
       </div>
       <div className="shrink-0 text-right">
@@ -1130,6 +1136,9 @@ export default function MarketEvents() {
   const [dateFrom,   setDateFrom]   = useState('')
   const [dateTo,     setDateTo]     = useState('')
   const [datePreset, setDatePreset] = useState<string>('all')   // 7d|30d|90d|6m|1y|all|custom
+  // Generation date filter (created_at)
+  const [genFrom,    setGenFrom]    = useState('')
+  const [genTo,      setGenTo]      = useState('')
   // Instrument impact filter
   const [instTicker, setInstTicker] = useState('')
   const [instMinScore, setInstMin]  = useState(0.3)
@@ -1177,6 +1186,8 @@ export default function MarketEvents() {
     if (minScore)  params.set('min_score', String(minScore))
     if (dateFrom)  params.set('date_from', dateFrom)
     if (dateTo)    params.set('date_to', dateTo)
+    if (genFrom)   params.set('gen_date_from', genFrom)
+    if (genTo)     params.set('gen_date_to', genTo)
     if (evaluated) params.set('evaluated', evaluated)
     if (instTicker) {
       params.set('instrument', instTicker)
@@ -1197,7 +1208,7 @@ export default function MarketEvents() {
       if (e.name === 'AbortError') return  // superseded by a newer load
     }
     setLoading(false)
-  }, [search, category, level, minScore, dateFrom, dateTo, evaluated,
+  }, [search, category, level, minScore, dateFrom, dateTo, genFrom, genTo, evaluated,
       instTicker, instMinScore, instDir, sortBy, sortDir])
 
   useEffect(() => {
@@ -1418,6 +1429,34 @@ export default function MarketEvents() {
                 </div>
               )}
             </div>
+
+            {/* ── Generation date filter ── */}
+            <div className="border-t border-slate-800/60 pt-2">
+              <div className="flex items-center gap-1.5 text-xs font-semibold mb-2 text-slate-500">
+                ⚡ Date de génération
+                {(genFrom || genTo) && (
+                  <button onClick={() => { setGenFrom(''); setGenTo('') }}
+                    className="ml-auto text-slate-600 hover:text-red-400 font-normal">× effacer</button>
+                )}
+              </div>
+              <div className="grid grid-cols-2 gap-2">
+                <div>
+                  <div className="text-xs text-slate-600 mb-0.5">Généré depuis</div>
+                  <input type="date" value={genFrom} onChange={e => setGenFrom(e.target.value)}
+                    className="w-full bg-dark-900 border border-slate-700 rounded px-2 py-1 text-slate-300 text-xs" />
+                </div>
+                <div>
+                  <div className="text-xs text-slate-600 mb-0.5">Généré jusqu'à</div>
+                  <input type="date" value={genTo} onChange={e => setGenTo(e.target.value)}
+                    className="w-full bg-dark-900 border border-slate-700 rounded px-2 py-1 text-slate-300 text-xs" />
+                </div>
+              </div>
+              {(genFrom || genTo) && (
+                <div className="text-xs text-blue-300 bg-blue-900/20 rounded px-2 py-1 border border-blue-800/30 mt-1.5">
+                  ⚡ Filtre actif sur date de génération (created_at)
+                </div>
+              )}
+            </div>
           </div>
         )}
 
@@ -1439,10 +1478,11 @@ export default function MarketEvents() {
         <div className="px-3 py-1 text-xs text-slate-600 border-b border-slate-800/30 flex items-center gap-2">
           <span>{loading ? '...' : total} événement{total !== 1 ? 's' : ''}</span>
           {instTicker && <span className="text-amber-400">· impact {instTicker}</span>}
-          {(category || level || search || minScore > 0 || evaluated || dateFrom || dateTo || instTicker) && (
+          {(category || level || search || minScore > 0 || evaluated || dateFrom || dateTo || genFrom || genTo || instTicker) && (
             <button onClick={() => {
               setSearch(''); setCategory(''); setLevel(''); setMinScore(0)
               setEvaluated(''); setDateFrom(''); setDateTo(''); setDatePreset('all')
+              setGenFrom(''); setGenTo('')
               setInstTicker(''); setInstDir(''); setInstMin(0.3); setSortBy('date')
             }} className="ml-auto text-xs text-slate-600 hover:text-red-400">× tout effacer</button>
           )}