refactor(signals): split the Track Record tab and cut the backtest page down

One tab stacked three things that all called themselves a track record:
realized paper P&L, setup-outcome grading under the rejected take-profit model,
and the backtest portfolio simulation. Split into Setups | Paper Trades |
Backtest, one subject each. `track` stays the Paper Trades slug so the legacy
/performance redirect keeps working. The grading diagnostic and its Evaluate /
Reset controls go with Backtest, not Paper Trades — reset_track_record deletes
trade_setups, not paper trades.

BacktestPanel 439 -> 175 lines. Its run settings alone were 106 lines of
hand-rolled sr-only radio cards for two binary choices; they are now two
Dropdowns and a button on one wrapping row, with the per-option prose moved into
the existing explainer. The amber warnings survive as a conditional slot, so a
non-default choice still announces itself but the common path is silent.

The recommendation printed eight findings at equal weight, burying the verdict
in tuning detail. `topic` now splits them: production, benchmark and robustness
stay inline, gate/exit/cutoff collapse behind a disclosure, and any WARNING or
LAGS item is promoted out of the collapsed group regardless of topic. No topic
chips — every backend string already self-prefixes, so a chip would render
"GATE | Gate: ...".

Portfolio metrics are now two tiers: five headline tiles for what the book
returned, then a smaller labelled row for how good that return was (Sortino,
Calmar (MAR), Gain/Pain, Profit Factor $, EV/trade). Reports cached before those
metrics existed hide the second row rather than showing a half-populated line of
dashes.

Extracted EquityCurveChart, PortfolioMonitorPanel and BacktestRecommendationCard,
plus a StatTile primitive and shared formatters for the duplication in the files
this touched. DashboardPage and OpenTradesPanel deliberately keep their own
copies — migrating them is separate scope.

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

frontend/src/lib/format.ts

@@ -72,3 +72,69 @@ export function formatDateTime(d: string): string {
     hour12: true,
   })}`;
 }
+
+// ── Metric display helpers ─────────────────────────────────────────────────
+// Shared by the Signals backtest/paper-trade panels. Dashboard and
+// OpenTradesPanel deliberately still carry their own copies — migrating them is
+// a separate change, not drive-by scope.
+
+/** R-multiple with an explicit sign. e.g. 1.2 → "+1.20R", null → "—" */
+export function fmtR(v: number | null | undefined): string {
+  if (v === null || v === undefined) return '—';
+  return `${v > 0 ? '+' : ''}${v.toFixed(2)}R`;
+}
+
+/** e.g. 12.34 → "12.3%" */
+export function fmtPct(v: number | null | undefined): string {
+  return v === null || v === undefined ? '—' : `${v.toFixed(1)}%`;
+}
+
+/** e.g. 12.34 → "+12.3%" */
+export function fmtSignedPct(v: number | null | undefined): string {
+  if (v === null || v === undefined) return '—';
+  return `${v > 0 ? '+' : ''}${v.toFixed(1)}%`;
+}
+
+/** Always rendered negative, whatever sign the source uses. 17.3 → "-17.3%" */
+export function fmtDrawdown(v: number | null | undefined): string {
+  return v === null || v === undefined ? '—' : `-${Math.abs(v).toFixed(1)}%`;
+}
+
+/** e.g. 15.3 → "15.3d" */
+export function fmtDays(v: number | null | undefined): string {
+  return v === null || v === undefined ? '—' : `${v.toFixed(1)}d`;
+}
+
+/** Unitless ratios — Sharpe, Sortino, Calmar, Gain/Pain, profit factor. */
+export function fmtRatio(v: number | null | undefined): string {
+  return v === null || v === undefined ? '—' : v.toFixed(2);
+}
+
+/**
+ * Bare amount, no currency symbol and no sign. e.g. 1234.5 → "1,234.50"
+ * Kept separate from fmtSignedMoney on purpose — they are not interchangeable.
+ */
+export function fmtMoney(v: number | null | undefined): string {
+  if (v === null || v === undefined) return '—';
+  return v.toLocaleString('en-US', {
+    minimumFractionDigits: 2,
+    maximumFractionDigits: 2,
+  });
+}
+
+/**
+ * Signed currency, using U+2212 for negatives. e.g. -12.3 → "−$12.30"
+ * Use wherever a value can go negative and the unit is money.
+ */
+export function fmtSignedMoney(v: number | null | undefined): string {
+  if (v === null || v === undefined) return '—';
+  return `${v >= 0 ? '+' : '−'}$${Math.abs(v).toFixed(2)}`;
+}
+
+/** Green above zero, red below, neutral at zero or null. */
+export function rColor(v: number | null | undefined): string {
+  if (v === null || v === undefined) return 'text-gray-400';
+  if (v > 0) return 'text-emerald-400';
+  if (v < 0) return 'text-red-400';
+  return 'text-gray-300';
+}