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/python/tests/test_input_validation.py

@@ -41,6 +41,18 @@ def test_roc_and_trix_have_default_periods():
     assert ta.TRIX() is not None
 
 
+def test_ichimoku_rejects_zero_and_non_increasing_periods():
+    with pytest.raises(ValueError):
+        ta.Ichimoku(0, 26, 52, 26)
+    with pytest.raises(ValueError):
+        ta.Ichimoku(9, 26, 52, 0)
+    # Periods must satisfy tenkan < kijun < senkou_b.
+    with pytest.raises(ValueError):
+        ta.Ichimoku(26, 9, 52, 26)
+    with pytest.raises(ValueError):
+        ta.Ichimoku(9, 52, 52, 26)
+
+
 def test_family_10_ehlers_rejects_invalid_parameters():
     with pytest.raises(ValueError):
         ta.SuperSmoother(0)