Normalize negative pagination params

[giwaov]

Summary

• Treat negative pageNumber values like missing values and default them to page 1.
• Treat negative perPage values like missing values and default them to 10.
• Add focused LoadArray coverage for negative pagination input.

Why

PageParams are accepted from JSON/RPC as signed integers. Negative values previously bypassed the zero-value defaults and could produce invalid skip indexes and pagination metadata.

Testing

• git diff --check
• Not run: Go toolchain is not installed in this environment.