Fix create and show commands for experimental models (#13741)

* x: make `ollama create --experimental` import from safetensors

This change allows pulling in safetensors models into the new experimental model format, and also
fixes the `ollama show` command to be able to correctly display the model information.

* gofumpt the linter

* gofumpt the linter again

* validate the model name

x/create/client/quantize_stub.go

@@ -0,0 +1,18 @@
+//go:build !mlx
+
+package client
+
+import (
+	"fmt"
+	"io"
+)
+
+// quantizeTensor is not available without MLX
+func quantizeTensor(r io.Reader, name, dtype string, shape []int32, quantize string) (qweightData, scalesData, qbiasData []byte, qweightShape, scalesShape, qbiasShape []int32, err error) {
+	return nil, nil, nil, nil, nil, nil, fmt.Errorf("quantization requires MLX support (build with mlx tag)")
+}
+
+// QuantizeSupported returns false when MLX is not available
+func QuantizeSupported() bool {
+	return false
+}