feat: robustness stats + dynamic recommendation; retire settled report sections

Robustness (answers 'is the edge just outliers?'):
- _bucket_stats gains median_net_r, profit_factor, and net_avg_r_ex_top5
  (expectancy with the top 5% of winners removed); shown as stat tiles.
- Portfolio sim gains per-calendar-year returns, shown in the sim table.

Dynamic recommendation ('What this backtest recommends' panel):
- _build_recommendation derives advice from the report's own numbers on
  every run — exit policy (target vs best hold, with sim CAGRs), which
  gate floors earn their keep (ablation Hold column), best momentum
  cutoff, book-vs-SPY verdict, and an outlier-dependence warning when
  the trimmed expectancy goes non-positive.

Retired (conclusions reached, tables removed from report + UI):
- Take-profit sweep (no interior optimum — fixed TP is the wrong tool
  for momentum), trailing sweep (converged to the hold-to-horizon exit),
  probability calibration (model is display-only by decision).
- _tp_primitives slimmed to _risk_and_stop_day; trailing machinery gone.

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

frontend/src/lib/types.ts

@@ -236,41 +236,16 @@ export interface BacktestBucket {
   worst_r?: number | null;
   avg_hold_days?: number | null;
   net_r_per_day?: number | null;
-}
-
-export interface BacktestCalibrationRow {
-  bucket: string;
-  n: number;
-  predicted_avg: number;
-  realized_hit_rate: number;
+  // Robustness: distribution shape, and expectancy without the top winners.
+  median_net_r?: number | null;
+  profit_factor?: number | null;
+  net_avg_r_ex_top5?: number | null;
 }
 
 export interface BacktestSweepRow extends BacktestBucket {
   min_momentum_percentile: number;
 }
 
-export interface BacktestTakeProfitRow {
-  tp_pct: number;
-  total: number;
-  wins: number;
-  hit_rate: number | null;
-  avg_r: number | null;
-  total_r: number | null;
-  net_avg_r?: number | null;
-  net_total_r?: number | null;
-}
-
-export interface BacktestTrailingRow {
-  trail_pct: number;
-  total: number;
-  wins: number;
-  win_rate: number | null;
-  avg_r: number | null;
-  total_r: number | null;
-  net_avg_r?: number | null;
-  net_total_r?: number | null;
-}
-
 export interface BacktestTimeExitRow {
   hold_days: number;
   total: number;
@@ -304,10 +279,17 @@ export interface BacktestPortfolioPolicy {
   avg_hold_days: number | null;
   skipped_book_full: number;
   spy_return_pct: number | null;
+  yearly_returns?: { year: number; return_pct: number | null }[];
   start_date: string;
   end_date: string;
 }
 
+export interface BacktestRecommendation {
+  headline: string | null;
+  items: { topic: string; text: string }[];
+  note?: string;
+}
+
 export interface BacktestPortfolioSim {
   params: {
     starting_capital: number;
@@ -359,11 +341,9 @@ export interface BacktestReport {
   sweep: BacktestSweepRow[];
   gate_ablation?: BacktestGateAblationRow[];
   gate_ablation_note?: string;
-  take_profit_sweep?: BacktestTakeProfitRow[];
-  trailing_sweep?: BacktestTrailingRow[];
   time_exit_sweep?: BacktestTimeExitRow[];
   portfolio_sim?: BacktestPortfolioSim;
-  calibration: BacktestCalibrationRow[];
+  recommendation?: BacktestRecommendation;
   signal_eval?: BacktestSignalEvalRow[];
   signal_eval_note?: string;
   note: string;