core: migrate to dankgo shared go modules, embed quickshell in DMS

binary to mount at runtime, -c or DMS_SHELL_DIR overrides required to
explicitly override embedded configuration

core/internal/shellembed/shellembed_bench_test.go

@@ -0,0 +1,52 @@
+package shellembed
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func benchDir(b *testing.B) string {
+	b.Helper()
+	dir, err := os.MkdirTemp("", "shellembed-bench-")
+	if err != nil {
+		b.Fatal(err)
+	}
+	b.Cleanup(func() {
+		filepath.WalkDir(dir, func(p string, d os.DirEntry, err error) error {
+			if err == nil && d.IsDir() {
+				os.Chmod(p, 0o755)
+			}
+			return nil
+		})
+		os.RemoveAll(dir)
+	})
+	return dir
+}
+
+func BenchmarkExtractWarm(b *testing.B) {
+	if !Available() {
+		b.Skip("no embedded UI in this build")
+	}
+	base := benchDir(b)
+	if _, err := Extract(base); err != nil {
+		b.Fatal(err)
+	}
+	b.ResetTimer()
+	for b.Loop() {
+		if _, err := Extract(base); err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func BenchmarkExtractCold(b *testing.B) {
+	if !Available() {
+		b.Skip("no embedded UI in this build")
+	}
+	for b.Loop() {
+		if _, err := Extract(benchDir(b)); err != nil {
+			b.Fatal(err)
+		}
+	}
+}