[New Feature] Support SAM 2.1 (#59)

* support sam 2.1

* refine config path and ckpt path

* update README

demo/frontend/src/common/components/annotations/ObjectPlaceholder.tsx

@@ -0,0 +1,46 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import {BLUE_PINK_FILL_BR} from '@/theme/gradientStyle';
+
+type Props = {
+  showPlus?: boolean;
+  onClick?: () => void;
+};
+
+export default function ObjectPlaceholder({showPlus = true, onClick}: Props) {
+  return (
+    <div
+      className={`relative ${BLUE_PINK_FILL_BR} h-12 w-12 md:h-20 md:w-20 shrink-0 rounded-lg`}
+      onClick={onClick}>
+      {showPlus && (
+        <div className="absolute left-1/2 top-1/2 -translate-x-1/2 -translate-y-1/2">
+          <svg
+            xmlns="http://www.w3.org/2000/svg"
+            width="16"
+            height="16"
+            viewBox="0 0 16 16"
+            fill="none">
+            <path
+              d="M16 7H9V0H7V7H0V9H7V16H9V9H16V7Z"
+              fill="#667788"
+              fillOpacity={1}
+            />
+          </svg>
+        </div>
+      )}
+    </div>
+  );
+}