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>

tests/unit/test_scheduler.py

@@ -82,6 +82,7 @@ class TestConfigureScheduler:
             "ticker_universe_sync",
             "outcome_evaluator",
             "alerts",
+            "market_regime",
         }
 
     def test_configure_is_idempotent(self):
@@ -94,6 +95,7 @@ class TestConfigureScheduler:
             "alerts",
             "data_collector",
             "fundamental_collector",
+            "market_regime",
             "outcome_evaluator",
             "rr_scanner",
             "sentiment_collector",