fix: display pagination cursors in all list commands

[leggetter]

Summary

Fixes #216

Previously, pagination cursors (next/prev) were not displayed to users in CLI output, even though they were available in the API responses. This made it impossible to paginate through large result sets (limit of 255 items).

This PR adds pagination cursor display to all list commands in both text and JSON output formats.

Changes

New Helper Functions (pkg/cmd/pagination_output.go)

• printPaginationInfo() - displays pagination cursors in text output
• marshalListResponseWithPagination() - includes pagination metadata in JSON output

Updated Commands

Applied pagination display to all 8 list commands:

• event list
• request list
• attempt list
• transformation list
• transformation executions
• connection list
• source list
• destination list

JSON Output Changes

• Before: Empty results returned []
• After: All responses return {"models": [...], "pagination": {...}}
• Pagination metadata always included (limit, order_by, dir, next, prev)

Text Output Changes

When pagination cursors exist, displays:

Pagination:
  Next: WzE3NDA2NTU4MTE2OTMsImV2dF...
  
To get the next page:
  hookdeck gateway event list --next WzE3NDA2NTU4MTE2OTMsImV2dF...

Test Updates

• Updated helper functions to handle new JSON response format
• Added comprehensive pagination workflow tests:
  • TestEventListPaginationWorkflow
  • TestRequestListPaginationWorkflow
  • TestAttemptListPaginationWorkflow
• Updated TestEventListJSON to verify pagination metadata

Test Plan

• All pagination acceptance tests pass
• Build succeeds with no errors
• Tests verify:
  • JSON includes pagination metadata
  • Text output shows pagination info
  • Next/prev cursors work correctly
  • Multiple pages contain different items