[jay23606]

Problem

TableController<TEntity>.QueryAsync returns PagedResult.NextLink as a query string only (for example $skip=50&$top=50). Datasync v6 clients and earlier resolve nextLink against the host root and send X-ZUMO-OPTIONS: nextLink=path to say so. With a query-only nextLink, those clients request the wrong URL, so paging fails once a result set exceeds PageSize.

Change

• Add IsLegacyClient(HttpRequest), which returns true when the X-ZUMO-OPTIONS header contains nextLink=path (case-insensitive).
• QueryAsync computes this once and passes it to BuildPagedResult, which passes it to CreateNextLink.
• For legacy clients, CreateNextLink returns the host-relative path with no leading slash, followed by the query string, for example tables/<table>?$skip=50&$top=50. Other clients keep the query-only format.

Testing

• dotnet test tests/CommunityToolkit.Datasync.Server.Test --filter "FullyQualifiedName~Query_LegacyClient_NextLinkIsRelativePath" passes on the fix. On the base source, with the same test file, it fails with Assert.StartsWith() Failure.
• dotnet test tests/CommunityToolkit.Datasync.Server.Test --filter "FullyQualifiedName!~Live" passes: 561 of 561.
• The unfiltered dotnet test tests/CommunityToolkit.Datasync.Server.Test exits with code 2. The live PostgreSQL tests fail with DockerUnavailableException because Docker is not running here. Those tests are not exercised by this change. CI needs to confirm the full suite.

Regression test: fails on base twice (/Assert.StartsWith() Failure/), passes on fix twice (dotnet test tests/CommunityToolkit.Datasync.Server.Test --filter "FullyQualifiedName~Query_LegacyClient_NextLinkIsRelativePath")

Fixes #629

[adrianhall]

This is not going to be accepted because legacy clients are not supported.