Refactor LTX-2 model structure

mlx_video/models/ltx_2/text_projection.py

@@ -0,0 +1,26 @@
+import mlx.core as mx
+import mlx.nn as nn
+
+
+class PixArtAlphaTextProjection(nn.Module):
+
+    def __init__(
+        self,
+        in_features: int,
+        hidden_size: int,
+        out_features: int | None = None,
+        bias: bool = True,
+    ):
+        
+        super().__init__()
+
+        out_features = out_features or hidden_size
+        self.linear1 = nn.Linear(in_features, hidden_size, bias=bias)
+        self.act = nn.GELU(approx="tanh")  # Must match PyTorch's approximate="tanh"
+        self.linear2 = nn.Linear(hidden_size, out_features, bias=bias)
+
+    def __call__(self, x: mx.array) -> mx.array:
+        x = self.linear1(x)
+        x = self.act(x)
+        x = self.linear2(x)
+        return x