Switch windows build to fully dynamic

Refactor where we store build outputs, and support a fully dynamic loading
model on windows so the base executable has no special dependencies thus
doesn't require a special PATH.

llm/shim_darwin.go

@@ -2,9 +2,13 @@ package llm
 
 import (
 	"embed"
+	"errors"
 	"fmt"
+	"io"
+	"io/fs"
 	"log"
 	"os"
+	"path/filepath"
 
 	"github.com/jmorganca/ollama/api"
 )
@@ -18,7 +22,7 @@ func newDynamicShimExtServer(library, model string, adapters, projectors []strin
 }
 
 func nativeInit(workdir string) error {
-	_, err := extractDynamicLibs(workdir, "llama.cpp/gguf/ggml-metal.metal")
+	err := extractPayloadFiles(workdir, "llama.cpp/gguf/ggml-metal.metal")
 	if err != nil {
 		if err == payloadMissing {
 			// TODO perhaps consider this a hard failure on arm macs?
@@ -30,3 +34,38 @@ func nativeInit(workdir string) error {
 	os.Setenv("GGML_METAL_PATH_RESOURCES", workdir)
 	return nil
 }
+
+func extractPayloadFiles(workDir, glob string) error {
+	files, err := fs.Glob(libEmbed, glob)
+	if err != nil || len(files) == 0 {
+		return payloadMissing
+	}
+
+	for _, file := range files {
+		srcFile, err := libEmbed.Open(file)
+		if err != nil {
+			return fmt.Errorf("read payload %s: %v", file, err)
+		}
+		defer srcFile.Close()
+		if err := os.MkdirAll(workDir, 0o755); err != nil {
+			return fmt.Errorf("create payload temp dir %s: %v", workDir, err)
+		}
+
+		destFile := filepath.Join(workDir, filepath.Base(file))
+		_, err = os.Stat(destFile)
+		switch {
+		case errors.Is(err, os.ErrNotExist):
+			destFile, err := os.OpenFile(destFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o755)
+			if err != nil {
+				return fmt.Errorf("write payload %s: %v", file, err)
+			}
+			defer destFile.Close()
+			if _, err := io.Copy(destFile, srcFile); err != nil {
+				return fmt.Errorf("copy payload %s: %v", file, err)
+			}
+		case err != nil:
+			return fmt.Errorf("stat payload %s: %v", file, err)
+		}
+	}
+	return nil
+}