Admin: add 'show version' (#11079)

### What problem does this PR solve?

```
admin> show version;
show_version
+-----------------------+
| version               |
+-----------------------+
| v0.21.0-241-gc6cf58d5 |
+-----------------------+
admin> \q
Goodbye!

```

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

common/versions.py

@@ -0,0 +1,50 @@
+#
+#  Copyright 2025 The InfiniFlow Authors. All Rights Reserved.
+#
+#  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 os
+import subprocess
+
+RAGFLOW_VERSION_INFO = "unknown"
+
+
+def get_ragflow_version() -> str:
+    global RAGFLOW_VERSION_INFO
+    if RAGFLOW_VERSION_INFO != "unknown":
+        return RAGFLOW_VERSION_INFO
+    version_path = os.path.abspath(
+        os.path.join(
+            os.path.dirname(os.path.realpath(__file__)), os.pardir, "VERSION"
+        )
+    )
+    if os.path.exists(version_path):
+        with open(version_path, "r") as f:
+            RAGFLOW_VERSION_INFO = f.read().strip()
+    else:
+        RAGFLOW_VERSION_INFO = get_closest_tag_and_count()
+    return RAGFLOW_VERSION_INFO
+
+
+def get_closest_tag_and_count():
+    try:
+        # Get the current commit hash
+        version_info = (
+            subprocess.check_output(["git", "describe", "--tags", "--match=v*", "--first-parent", "--always"])
+            .strip()
+            .decode("utf-8")
+        )
+        return version_info
+    except Exception:
+        return "unknown"