refactor: 拆分 module.py 为 components 子包

- rope/linear/norm/embedding/mlp/attention/decoder_block 各自独立文件
- 依赖单向无循环
- 公开接口不变，外部无需修改

astrai/model/components/mlp.py

@@ -0,0 +1,18 @@
+import torch.nn as nn
+import torch.nn.functional as F
+from torch import Tensor
+
+from astrai.model.components.linear import Linear
+
+
+class MLP(nn.Module):
+    def __init__(self, dim: int, dim_feed_forward: int):
+        super().__init__()
+        self.up = Linear(dim, dim_feed_forward)
+        self.gate = Linear(dim, dim_feed_forward)
+        self.down = Linear(dim_feed_forward, dim)
+
+    def forward(self, x: Tensor) -> Tensor:
+        gated = self.up(x) * F.silu(self.gate(x))
+        out = self.down(gated)
+        return out