feat(scans): polish scans list card — drop noise, surface commit SHA

[sachiniyer]

Summary

Two small triage-friendly tweaks to scans list card output (audit items #10 and #11 — bundled because they both touch Formattable for Scan):

1. Header parenthetical (#10)
Drop the (N Open) parenthetical when it would be noise:

• total == 0 — leading 0 Bugs Found already says nothing; (0 Open) is boilerplate
• open == total — (N Open) just restates the leading number

Otherwise the existing "{repo} N Bugs Found (M Open)" form is preserved.

2. Commit row (#11)
Surface Scan.commit_sha (truncated to 7 chars, matching format_introduced_in's blame style) so users can answer "did this scan run on the current main?" without an extra round-trip. Conditional — omitted when commit_sha is null/absent so older scans stay quiet.

Test refactor

Existing scan-card tests addressed pairs[N] by numeric index, which would silently break once the new conditional Commit row shifts later positions. Rewrote them to look up by key name via a small scan_pair helper.

Testing

Automated, run locally and passing:

• cargo test — full suite green. New tests:
  • scan_card_header_drops_parenthetical_when_total_is_zero → "usedetail/cli 0 Bugs Found"
  • scan_card_header_drops_parenthetical_when_open_equals_total → "usedetail/cli 7 Bugs Found" (7 found, 7 open)
  • scan_card_header_keeps_parenthetical_when_partially_resolved → still emits (3 Open) when partial
  • scan_card_includes_short_commit_sha → 24-char sha truncated to "deadbee"
  • scan_card_omits_commit_when_null
  • Existing scan_card_workflow_id_present etc. updated to look up by key
• cargo clippy -- -D warnings — clean
• cargo fmt --check — clean
• cargo xtask check — clean (no flag changes; HELP.md unchanged)

Manual end-to-end against live API (usedetail/detail):

1. usedetail/detail 0 Bugs Found              ← was "0 Bugs Found (0 Open)"
    Status       complete
    Scan Type    -
    Initiator    scheduler
    Workflow ID  wr_387e02f8-…
    Created      2026-05-06 11:23:02 -07:00
2. usedetail/detail 0 Bugs Found              ← parenthetical dropped
    Status       complete
    Scan Type    recentChanges
    Initiator    scheduler
    Commit       5373780                       ← new row, conditional
    Workflow ID  wr_d0b4fdfd-…
    Created      2026-05-06 11:22:34 -07:00
3. usedetail/detail 1 Bugs Found (0 Open)     ← parenthetical kept (open ≠ total)
    Status       complete
    Scan Type    recentChanges
    Initiator    scheduler
    Commit       aa4ba49
    Workflow ID  wr_27be25a4-…
    Created      2026-05-05 16:36:24 -07:00

• Verified the older scan Chore: Update readme to correct download link #4 with no commitSha cleanly omits the Commit row.
• The open == total branch wasn't representable in usedetail/detail's recent scans (everything is resolved), so it's covered by unit test only.

🤖 Generated with Claude Code

[cubic-dev-ai]

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