[refactor] move tests to tests/, add pytest functions and main() entrypoints

- Moved src/tests/ → tests/
- Added test_* functions with assertions to script-style test files
- Added main() to each so IDEs offer it as a separate run target from pytest
- Fixed cupy_test.py: remove spurious x_gpu += x_cpu, fix duplicate xlabel

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_label.py

@@ -0,0 +1,47 @@
+import matplotlib.pyplot as plt
+
+from rbm.matrix import np
+from label.label import Label
+
+if __name__ == "__main__":
+	voc_size = 100
+	do_train = True
+	work_dir = "../../results"
+	prj_root = "/home/jens/work/repos/Rbm"
+
+	# Create Labeler
+	label_w = 5
+	label_h = 5
+	enc = Label(voc_size, label_w*label_h, Label.EncodingType.Binary, work_dir)
+
+	# Load
+	enc.fitter.load()
+
+	# Train
+	if do_train:
+		train_labels = list(range(voc_size))
+		enc.fit(train_labels)
+		enc.fitter.save()
+
+	# Encode test labels
+	test_labels = np.array([1, 23, 99, 37, 55, 7, 31, 10, 19, 70])
+	encoded, binary_labels = enc.encode(test_labels)
+
+	# Decode
+	decoded_soft = enc.decode(encoded)
+	decode_hard = (decoded_soft > 0.90).astype(int)
+
+	print(f"Soft Error: {np.sum((decoded_soft - binary_labels) ** 2)}")
+	print(f"Hard Error: {np.sum((decode_hard - binary_labels) ** 2)}")
+
+	fig, axes = plt.subplots(1, len(encoded), figsize=(12, 3))
+	for index, inp in enumerate(encoded):
+		img = np.reshape(inp, (label_w, label_h))
+		axes[index].imshow(img)
+		axes[index].axis('off')
+		axes[index].set_title(f'{test_labels[index]}')
+
+	plt.show()
+
+	print("Test: [passed]")
+