feat(wan): Add Wan2.2 I2V support

tests/wan_test_helpers.py

@@ -0,0 +1,19 @@
+"""Shared test helpers for Wan test modules."""
+
+
+def _make_tiny_config():
+    """Create a tiny WanModelConfig for testing."""
+    from mlx_video.models.wan.config import WanModelConfig
+    config = WanModelConfig()
+    # Override to tiny values
+    config.dim = 64
+    config.ffn_dim = 128
+    config.num_heads = 4
+    config.num_layers = 2
+    config.in_dim = 4
+    config.out_dim = 4
+    config.patch_size = (1, 2, 2)
+    config.freq_dim = 32
+    config.text_dim = 32
+    config.text_len = 8
+    return config