feat(pr-report): restore GitHub Check Run creation

[diogot]

File: Sources/Xproject/Services/PRReportService.swift
Lines: 710-715

The reportToGitHubWithIdentifier function no longer creates GitHub Check Runs. It only uses PRCommentReporter and PRReviewReporter, leaving checkRunURL permanently nil.

Impact

• The checkName and conclusion parameters are declared but unused
• GitHub Actions runs will post comments but will not surface a failing/successful check on the PR
• This may break the documented "GitHub PR reporting via Checks API" flow in docs/configuration-reference.md

Decision Needed

• Was this intentional? If so, documentation needs updating
• Should Check Runs be reinstated alongside comments?
• Should there be a configuration option to choose between Check Runs and PR comments?

Originally identified in PR #29.