Fix event cursor pagination links

[niemyjski]

Summary

• Stop cursor-paged responses from emitting rel="next" when the repository says there are no more results.
• Add regression coverage for partial final cursor pages and link helper generation.

Root Cause

• EventController passed the last row sort token into OkWithResourceLinks for every non-empty cursor page.
• OkWithResourceLinks generated a next link solely from a non-empty after token, ignoring HasMore, so a partial final page advertised a phantom cursor.

Validation

• dotnet test -- --filter-class Exceptionless.Tests.Miscellaneous.EfficientPagingTests
• dotnet test -- --filter-class Exceptionless.Tests.Controllers.EventControllerTests
• Local Aspire UI: /next/event/all?limit=10 showed Page 1 of 2, then Page 2 of 2 with 4 rows and Next disabled.

Breaking Changes

None.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Exceptionless.AppHost	39%	40%	134	❌
Exceptionless.Core	70%	63%	8002	➖
Exceptionless.Insulation	24%	23%	203	❌
Exceptionless.Web	72%	62%	4165	➖
Summary	69% (14262 / 20628)	62% (7409 / 12046)	12504	➖