Add local batched Git blob reader

internal/git/source_test.go

@@ -62,6 +62,13 @@ func TestCandidateObjectReadsStayLocalInPartialClones(t *testing.T) {
 			if !errors.As(err, &exitError) {
 				t.Fatalf("blob error %v lost its Git process cause", err)
 			}
+			reader := NewBlobReader(t.Context(), repository)
+			if _, err := reader.Read(t.Context(), blob); err == nil || !strings.Contains(err.Error(), "missing") {
+				t.Fatalf("batch blob read error = %v, want missing-object inspection error", err)
+			}
+			if err := reader.Close(); err != nil {
+				t.Fatalf("close missing-object batch reader: %v", err)
+			}
 			if data, err := os.ReadFile(attempts); !errors.Is(err, os.ErrNotExist) {
 				t.Fatalf("object inspection invoked remote transport: %q, %v", data, err)
 			}