B9: raise ValueError instead of panicking on non-contiguous arrays

Every Python batch() did prices.as_slice().expect("contiguous"), so a
non-contiguous NumPy input (e.g. a strided view) aborted with a Rust
panic instead of a catchable exception. as_slice() failures now map to a
PyValueError pointing at np.ascontiguousarray; the scalar / MACD /
Bollinger batch methods that returned a bare array were lifted to
PyResult so the error can propagate. Adds input-validation tests
(non-contiguous arrays, unequal-length candle batches, ROC/TRIX
defaults). All 60 Python tests pass against the freshly built wheel.

bindings/python/tests/test_input_validation.py

@@ -0,0 +1,41 @@
+"""Input-validation tests: malformed NumPy inputs raise ValueError, not panics."""
+
+from __future__ import annotations
+
+import numpy as np
+import pytest
+
+import wickra as ta
+
+
+def test_non_contiguous_array_raises_value_error():
+    # A strided view is not C-contiguous; batch() must reject it cleanly.
+    base = np.linspace(1.0, 100.0, 60)
+    non_contiguous = base[::2]
+    assert not non_contiguous.flags["C_CONTIGUOUS"]
+    with pytest.raises(ValueError):
+        ta.SMA(5).batch(non_contiguous)
+
+
+def test_ascontiguousarray_recovers():
+    base = np.linspace(1.0, 100.0, 60)
+    fixed = np.ascontiguousarray(base[::2])
+    out = ta.SMA(5).batch(fixed)
+    assert out.shape == fixed.shape
+
+
+def test_unequal_length_candle_batch_raises(ohlc_series):
+    high, low, close = ohlc_series
+    short = low[:-1]
+    with pytest.raises(ValueError):
+        ta.ATR(14).batch(high, short, close)
+    with pytest.raises(ValueError):
+        ta.WilliamsR(14).batch(high, short, close)
+    with pytest.raises(ValueError):
+        ta.Aroon(14).batch(high, short)
+
+
+def test_roc_and_trix_have_default_periods():
+    # ROC/TRIX gained constructor defaults matching the TA-Lib convention.
+    assert ta.ROC().period == 10
+    assert ta.TRIX() is not None