feat(family-13): add Ichimoku + Heikin-Ashi (#50)

Two new indicators in a brand-new "Ichimoku & alternative charts"
family:

- `Ichimoku` (Ichimoku Kinko Hyo): the full five-line cloud system
  (Tenkan-sen, Kijun-sen, Senkou Span A/B, Chikou Span). Classic
  (9, 26, 52, 26) defaults; configurable. Forward displacement is
  handled in an O(1) ring buffer so the visible Senkou A/B at bar n
  are the values computed at bar n-displacement.
- `HeikinAshi`: recursive candle smoothing transform emitting a
  four-field synthetic candle. Seeds ha_open from (open+close)/2 on
  the first bar.

Touchpoints: core + unit tests, mod.rs/lib.rs re-exports, Python +
Node + WASM bindings (multi-output via PyArray2 / interleaved Vec<f64>
/ Object+Float64Array), Python tests across smoke/new-indicators/
input-validation, Node parity tests, fuzz target (Candle), benches,
README family table + counter (71 -> 73, 8 -> 9 families), CHANGELOG.

Note: Renko, Kagi, and Point & Figure from the family-13 ideas list
are intentionally skipped. They are bar generators (the bar boundary
is defined by price moves, not by a fixed time interval) rather than
indicators that consume a candle stream, and belong in wickra-data
as candle/tick transforms alongside the existing tick-to-candle
aggregator and resampler.

bindings/node/__tests__/indicators.test.js

@@ -231,6 +231,9 @@ const multi = {
   TDRiskLevel: { make: () => new wickra.TDRiskLevel(4, 9), fields: ['buyRisk', 'sellRisk'], step: (ind, i) => ind.update(high[i], low[i], close[i]), batch: (ind) => ind.batch(high, low, close) },
   // Family 10: Ehlers / Cycle (multi-output)
   MAMA: { make: () => new wickra.MAMA(0.5, 0.05), fields: ['mama', 'fama'], step: (ind, i) => ind.update(close[i]), batch: (ind) => ind.batch(close) },
+  // Family 13: Ichimoku & alternative charts
+  Ichimoku: { make: () => new wickra.Ichimoku(9, 26, 52, 26), fields: ['tenkan', 'kijun', 'senkouA', 'senkouB', 'chikou'], step: (ind, i) => ind.update(high[i], low[i], close[i]), batch: (ind) => ind.batch(high, low, close) },
+  HeikinAshi: { make: () => new wickra.HeikinAshi(), fields: ['open', 'high', 'low', 'close'], step: (ind, i) => ind.update(open[i], high[i], low[i], close[i]), batch: (ind) => ind.batch(open, high, low, close) },
 };
 
 for (const [name, d] of Object.entries(multi)) {
@@ -357,6 +360,27 @@ test('LinRegAngle of a unit-slope series is 45 degrees', () => {
   assert.ok(Math.abs(out[4] - 45) < 1e-9);
 });
 
+test('Ichimoku classic warmup is 77 and tenkan emits at bar 9', () => {
+  const ichi = new wickra.Ichimoku(9, 26, 52, 26);
+  assert.equal(ichi.warmupPeriod(), 77);
+  const n = 30;
+  const h = Array.from({ length: n }, (_, i) => 100 + i + 2);
+  const l = Array.from({ length: n }, (_, i) => 100 + i - 2);
+  const c = Array.from({ length: n }, (_, i) => 100 + i + 1);
+  const out = ichi.batch(h, l, c);
+  for (let i = 0; i < 8; i++) {
+    assert.ok(Number.isNaN(out[i * 5]), `tenkan should be NaN at bar ${i}`);
+  }
+  assert.ok(!Number.isNaN(out[8 * 5]), 'tenkan should be defined at bar 9');
+});
+
+test('HeikinAshi first bar seeds from real open and close', () => {
+  const ha = new wickra.HeikinAshi();
+  const out = ha.update(10, 12, 9, 11);
+  assert.ok(Math.abs(out.open - (10 + 11) / 2) < 1e-12);
+  assert.ok(Math.abs(out.close - (10 + 12 + 9 + 11) / 4) < 1e-12);
+});
+
 test('PercentageTrailingStop seeds and ratchets', () => {
   const s = new wickra.PercentageTrailingStop(10);
   assert.ok(Math.abs(s.update(100) - 90) < 1e-9);