feat(covgate): render --exclude packages as SKIPPED rows in coverage table

[ben-miru]

Summary

• Render each --excluded package as a SKIPPED row in the per-package coverage table with --- placeholders for COVERAGE/REQUIRED/TIME, grouped at the end after measured rows.
• Widen the STATUS column from 6 to 7 chars so SKIPPED fits without breaking alignment of existing PASS/FAIL/LOOSE rows.
• Follow-up to feat(covgate): add --exclude flag to skip packages from coverage measurement #29: the existing Excluded N package(s) summary line told users how many packages were excluded but not which ones. This change surfaces them by name. The summary line is preserved and the pass/fail tally is unaffected — SKIPPED rows never flip a successful run to failure.

Sample output

Checking per-package coverage (default minimum: 80.0%)...

Excluded 1 package(s) from coverage measurement
STATUS    COVERAGE  REQUIRED      TIME  PACKAGE
-------   --------  --------  --------  -------
PASS         90.0%     80.0%      0.5s  pkg/a
PASS         85.2%     80.0%      0.4s  pkg/c
SKIPPED        ---       ---       ---  pkg/b

Total time: 0.9s
All packages meet minimum coverage requirement

Test plan

• SKIPPED row renders for each --excluded package
• SKIPPED rows appear after all measured rows in the table
• SKIPPED packages do not count toward the failure tally (run succeeds when all measured packages pass)
• All-excluded case: run succeeds with every package as a SKIPPED row
• Existing TestRun_Exclude subtests pass with updated assertions
• ./scripts/preflight.sh reports === All checks passed ===

Full design and rationale: plans/completed/20260515-covgate-skipped-rows.md.

Claude Code