Setup views: primary-target column, floor-target prune, liveness cutoff

Three follow-ups to the gate probability floor (8f41143):

- Signals table shows the starred primary target (shared primaryTarget
  helper) instead of an independently computed max-probability best,
  so Overview, Signals and ticker details agree by construction.
- Targets pinned at the 3% probability clamp floor collapse to the
  nearest one (enhance_trade_setup + backtest candidates in parity):
  floor-pinned levels are indistinguishable to the model, so farther
  ones were duplicate 3% rows inviting lottery headlines.
- get_trade_setups only returns setups re-emitted within
  LIVE_SETUP_MAX_AGE_DAYS (3): an older latest row means the daily
  scan no longer confirms the setup, and such rows otherwise surface
  forever on Overview/Signals/ticker/alerts. History endpoints keep
  full history.

Backtest on the Jul-3 snapshot is metric-identical to the gate-floor
run on all qualified stats (1089 qualified, Sharpe 2.02, CAGR +49.6%,
DD -15.8%): the prune only removes noise the gate already rejected.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/signals/SetupsPanel.tsx

@@ -2,7 +2,7 @@ import { useEffect, useMemo, useState } from 'react';
 import { useMutation, useQueryClient } from '@tanstack/react-query';
 import { useActivation } from '../../hooks/useActivation';
 import { useTrades } from '../../hooks/useTrades';
-import { qualifiesSetup, activationSummary } from '../../lib/qualification';
+import { qualifiesSetup, activationSummary, primaryTargetProbability } from '../../lib/qualification';
 import { TradeTable, type SortColumn, type SortDirection, computeTradeAnalysis } from '../scanner/TradeTable';
 import { SkeletonTable } from '../ui/Skeleton';
 import { useToast } from '../ui/Toast';
@@ -42,8 +42,8 @@ function getComputedValue(trade: TradeSetup, column: SortColumn): number {
     case 'stop_pct': return analysis.stop_pct;
     case 'target_pct': return analysis.target_pct;
     case 'confidence_score': return trade.confidence_score ?? -1;
-    case 'best_target_probability':
-      return trade.targets?.length ? Math.max(...trade.targets.map((t) => t.probability)) : -1;
+    case 'primary_target_probability':
+      return primaryTargetProbability(trade) ?? -1;
     case 'risk_level':
       if (trade.risk_level === 'Low') return 1;
       if (trade.risk_level === 'Medium') return 2;
@@ -78,7 +78,7 @@ function sortTrades(
       case 'stop_pct':
       case 'target_pct':
       case 'confidence_score':
-      case 'best_target_probability':
+      case 'primary_target_probability':
       case 'risk_level':
         cmp = getComputedValue(a, column) - getComputedValue(b, column);
         break;