feat: add records endpoint with all CRUD and query methods

Implement Record, RecordFieldValue, SaveRecordRequest,
QueryRecordsRequest, BatchGetRecordsRequest, and BatchDeleteRecordsRequest
models. Add 7 endpoint methods: list_records, get_record, save_record,
delete_record, batch_get_records, query_records, batch_delete_records.
Add 9 tests covering all methods including parameterized queries.

src/endpoints/mod.rs

@@ -1,3 +1,4 @@
 mod apps;
 mod fields;
 mod ping;
+mod records;

src/endpoints/records.rs

@@ -0,0 +1,111 @@
+use reqwest::Method;
+
+use crate::client::OnspringClient;
+use crate::error::Result;
+use crate::models::{
+    BatchDeleteRecordsRequest, BatchGetRecordsRequest, CollectionResponse, DataFormat,
+    PagedResponse, PagingRequest, QueryRecordsRequest, Record, SaveRecordRequest,
+    SaveRecordResponse,
+};
+
+impl OnspringClient {
+    /// Gets a paginated collection of records for a given app.
+    pub async fn list_records(
+        &self,
+        app_id: i32,
+        paging: Option<PagingRequest>,
+        field_ids: Option<&[i32]>,
+        data_format: Option<DataFormat>,
+    ) -> Result<PagedResponse<Record>> {
+        let path = format!("/Records/appId/{}", app_id);
+        let mut query = Vec::new();
+        if let Some(p) = paging {
+            query.push(("PageNumber", p.page_number.to_string()));
+            query.push(("PageSize", p.page_size.to_string()));
+        }
+        if let Some(ids) = field_ids {
+            let ids_str = ids
+                .iter()
+                .map(|id| id.to_string())
+                .collect::<Vec<_>>()
+                .join(",");
+            query.push(("fieldIds", ids_str));
+        }
+        if let Some(fmt) = data_format {
+            query.push(("dataFormat", format!("{:?}", fmt)));
+        }
+        let query_refs: Vec<(&str, String)> = query.iter().map(|(k, v)| (*k, v.clone())).collect();
+        self.request(Method::GET, &path, &query_refs, Option::<&()>::None)
+            .await
+    }
+
+    /// Gets a record by its identifier.
+    pub async fn get_record(
+        &self,
+        app_id: i32,
+        record_id: i32,
+        field_ids: Option<&[i32]>,
+        data_format: Option<DataFormat>,
+    ) -> Result<Record> {
+        let path = format!("/Records/appId/{}/recordId/{}", app_id, record_id);
+        let mut query = Vec::new();
+        if let Some(ids) = field_ids {
+            let ids_str = ids
+                .iter()
+                .map(|id| id.to_string())
+                .collect::<Vec<_>>()
+                .join(",");
+            query.push(("fieldIds", ids_str));
+        }
+        if let Some(fmt) = data_format {
+            query.push(("dataFormat", format!("{:?}", fmt)));
+        }
+        let query_refs: Vec<(&str, String)> = query.iter().map(|(k, v)| (*k, v.clone())).collect();
+        self.request(Method::GET, &path, &query_refs, Option::<&()>::None)
+            .await
+    }
+
+    /// Creates or updates a record.
+    pub async fn save_record(&self, request: SaveRecordRequest) -> Result<SaveRecordResponse> {
+        self.request(Method::PUT, "/Records", &[], Some(&request))
+            .await
+    }
+
+    /// Deletes a record by its identifier.
+    pub async fn delete_record(&self, app_id: i32, record_id: i32) -> Result<()> {
+        let path = format!("/Records/appId/{}/recordId/{}", app_id, record_id);
+        self.request_no_content(Method::DELETE, &path, &[], Option::<&()>::None)
+            .await
+    }
+
+    /// Gets a batch of records.
+    pub async fn batch_get_records(
+        &self,
+        request: BatchGetRecordsRequest,
+    ) -> Result<CollectionResponse<Record>> {
+        self.request(Method::POST, "/Records/batch-get", &[], Some(&request))
+            .await
+    }
+
+    /// Queries records using a filter expression.
+    pub async fn query_records(
+        &self,
+        request: QueryRecordsRequest,
+        paging: Option<PagingRequest>,
+    ) -> Result<PagedResponse<Record>> {
+        let mut query = Vec::new();
+        if let Some(p) = paging {
+            query.push(("PageNumber", p.page_number.to_string()));
+            query.push(("PageSize", p.page_size.to_string()));
+        }
+        let query_refs: Vec<(&str, String)> = query.iter().map(|(k, v)| (*k, v.clone())).collect();
+        self.request(Method::POST, "/Records/Query", &query_refs, Some(&request))
+            .await
+    }
+
+    /// Deletes a batch of records.
+    pub async fn batch_delete_records(&self, request: BatchDeleteRecordsRequest) -> Result<()> {
+        self.request_no_content(Method::POST, "/Records/batch-delete", &[], Some(&request))
+            .await
+    }
+}