fix(nodejs): reject listNamespaces limit above i32::MAX instead of wrapping (#4584)

## Summary

Fixes #4583.

`Connection::list_namespaces` narrowed `Option<u32>` to `i32` with an
unchecked `as` cast, so a JavaScript `limit` between 2^31 and 2^32 - 1
(e.g. `3000000000`) wrapped negative before reaching
`ListNamespacesRequest`. The server received a negative page size
instead of a clear client-side error.

Replaced the cast with a `checked_limit` helper using `i32::try_from`,
returning `napi::Error::from_reason` on overflow, matching the existing
`try_from` validation used for `limit` elsewhere in the same file.

## Tests

Unit tests cover the wrap case (`u32` values above `i32::MAX` reject),
the boundary (`i32::MAX` passes), and `None`/zero passthrough. `cargo
test -p lancedb-nodejs` passes 8/8 and `pnpm build` compiles the binding
and TypeScript definitions cleanly.

nodejs/src/connection.rs

@@ -673,7 +673,7 @@ impl Connection {
         let req = ListNamespacesRequest {
             id: namespace_path,
             page_token,
-            limit: limit.map(|l| l as i32),
+            limit: checked_limit(limit)?,
             ..Default::default()
         };
         let resp = self
@@ -787,3 +787,33 @@ impl Connection {
             .default_error()
     }
 }
+
+fn checked_limit(limit: Option<u32>) -> napi::Result<Option<i32>> {
+    limit
+        .map(i32::try_from)
+        .transpose()
+        .map_err(|_| napi::Error::from_reason("limit must not exceed 2147483647"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::checked_limit;
+
+    #[test]
+    fn checked_limit_rejects_values_above_i32_max() {
+        // u32 values above i32::MAX wrapped negative through `as i32`,
+        // sending a negative page size to the server.
+        assert!(checked_limit(Some(3_000_000_000)).is_err());
+        assert!(checked_limit(Some(u32::MAX)).is_err());
+    }
+
+    #[test]
+    fn checked_limit_passes_boundary_and_missing_values() {
+        assert_eq!(
+            checked_limit(Some(i32::MAX as u32)).unwrap(),
+            Some(i32::MAX)
+        );
+        assert_eq!(checked_limit(Some(0)).unwrap(), Some(0));
+        assert_eq!(checked_limit(None).unwrap(), None);
+    }
+}