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/lib/qualification.ts

@@ -1,4 +1,4 @@
-import type { ActivationConfig, TradeSetup } from './types';
+import type { ActivationConfig, TradeSetup, TradeTarget } from './types';
 
 const HIGH_CONVICTION_ACTIONS = new Set(['LONG_HIGH', 'SHORT_HIGH']);
 
@@ -16,15 +16,18 @@ function actionDirection(action: TradeSetup['recommended_action']): 'long' | 'sh
   return 'neutral';
 }
 
-export function bestTargetProbability(setup: TradeSetup): number {
-  return setup.targets?.length ? Math.max(...setup.targets.map((t) => t.probability)) : 0;
+/** The starred primary target (the one the headline R:R refers to), falling
+ * back to the most likely target when no star is stored. */
+export function primaryTarget(setup: TradeSetup): TradeTarget | null {
+  const starred = setup.targets?.find((t) => t.is_primary);
+  if (starred) return starred;
+  if (!setup.targets?.length) return null;
+  return [...setup.targets].sort((a, b) => b.probability - a.probability)[0];
 }
 
 /** Probability of the starred primary target (the one the headline R:R refers to). */
 export function primaryTargetProbability(setup: TradeSetup): number | null {
-  const primary = setup.targets?.find((t) => t.is_primary);
-  if (primary) return primary.probability;
-  return setup.targets?.length ? bestTargetProbability(setup) : null;
+  return primaryTarget(setup)?.probability ?? null;
 }
 
 /** R:R recomputed from the current price (0 if no reward/risk left). */