fix: paginate Project items for issue readiness

[codeforester]

Summary

• replace the bounded gh project item-list --limit 1000 readiness lookup with a paginated REST Project-items lookup
• resolve organization and user Project owners and request the five required readiness fields
• preserve empty-item versus GitHub API failure handling

Issue

Fixes #2438

Validation

• env BASE_BASH_LIBS_DIR=/Users/rameshhp/work/base-bash-libs/lib/bash bats cli/bash/commands/basectl/tests/gh.bats (74 passing)
• live basectl gh issue readiness 2438 --repo basefoundry/base --project-owner basefoundry --project-number 10 (ready; Project fields ok)

Dependencies

• None.