feat(mongodb): improve GridFS manager filtering and sorting

* docs: add GridFS manager filter and sort design

* feat: improve GridFS manager filtering and sorting

crates/dbx-core/src/db/mongo_driver.rs

@@ -207,12 +207,15 @@ pub async fn list_gridfs_files(
     client: &Client,
     database: &str,
     bucket: &str,
+    filter: Option<&str>,
+    sort: Option<&str>,
 ) -> Result<Vec<MongoGridFsFileInfo>, String> {
     let bucket = normalized_gridfs_bucket_name(bucket)?;
     let collection_name = format!("{bucket}.files");
     let collection = client.database(database).collection::<Document>(&collection_name);
-    let mut cursor =
-        collection.find(doc! {}).sort(doc! { "uploadDate": -1_i32, "_id": -1_i32 }).await.map_err(|e| e.to_string())?;
+    let filter_doc = gridfs_file_filter_document(filter)?;
+    let sort_doc = gridfs_file_sort_document(sort)?;
+    let mut cursor = collection.find(filter_doc).sort(sort_doc).await.map_err(|e| e.to_string())?;
     let mut files = Vec::new();
     while cursor.advance().await.map_err(|e| e.to_string())? {
         let doc = cursor.deserialize_current().map_err(|e| e.to_string())?;
@@ -221,6 +224,26 @@ pub async fn list_gridfs_files(
     Ok(files)
 }
 
+fn gridfs_file_filter_document(filter: Option<&str>) -> Result<Document, String> {
+    match filter {
+        Some(raw) if !raw.trim().is_empty() => {
+            let json: serde_json::Value = serde_json::from_str(raw).map_err(|e| format!("Invalid filter JSON: {e}"))?;
+            json_filter_to_document(&json)
+        }
+        _ => Ok(doc! {}),
+    }
+}
+
+fn gridfs_file_sort_document(sort: Option<&str>) -> Result<Document, String> {
+    match sort {
+        Some(raw) if !raw.trim().is_empty() => {
+            let json: serde_json::Value = serde_json::from_str(raw).map_err(|e| format!("Invalid sort JSON: {e}"))?;
+            json_object_to_document(&json).map_err(|e| format!("Invalid sort: {e}"))
+        }
+        _ => Ok(doc! { "uploadDate": -1_i32, "_id": -1_i32 }),
+    }
+}
+
 pub async fn gridfs_bucket_summary(
     client: &Client,
     database: &str,
@@ -1583,6 +1606,16 @@ mod tests {
         assert_eq!(info.aliases, Some(vec!["archive".to_string(), "nightly".to_string()]));
     }
 
+    #[test]
+    fn gridfs_file_sort_uses_upload_date_desc_by_default() {
+        assert_eq!(gridfs_file_sort_document(None).unwrap(), doc! { "uploadDate": -1_i32, "_id": -1_i32 });
+    }
+
+    #[test]
+    fn gridfs_file_sort_parses_explicit_sort_json() {
+        assert_eq!(gridfs_file_sort_document(Some(r#"{"filename":1}"#)).unwrap(), doc! { "filename": 1_i64 });
+    }
+
     #[test]
     fn json_object_to_document_parses_find_projection() {
         let value = serde_json::json!({