add market-regime guard (SPY trend) — inform + warn

New market_regime_service computes a benchmark (SPY) trend from its 50/200-day
SMAs, cached in a SystemSetting and refreshed by a nightly job; GET /market/regime
exposes it. Dashboard shows a regime banner; setup cards flag a counter-trend
caution when a setup fights the regime (LONG in a bearish market / SHORT in a
bullish one). Informational only — nothing is suppressed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/services/admin_service.py

@@ -483,6 +483,7 @@ VALID_JOB_NAMES = {
     "ticker_universe_sync",
     "outcome_evaluator",
     "alerts",
+    "market_regime",
 }
 
 JOB_LABELS = {
@@ -493,6 +494,7 @@ JOB_LABELS = {
     "ticker_universe_sync": "Ticker Universe Sync",
     "outcome_evaluator": "Outcome Evaluator",
     "alerts": "Alerts Dispatcher",
+    "market_regime": "Market Regime",
 }