Adds tests/dashboard/test_scorecard_service.py with 31 unit tests
covering gaps not addressed in test_scorecards.py:
- _aggregate_metrics: test.execution events, PR-closed-without-merge,
push with no num_commits key, issue/PR events with number=0,
untracked agent with agent_id field passthrough
- _detect_patterns: boundary conditions (< 3 PRs threshold, exactly 80%
merge rate, commit count boundary at 10 vs 11, token net boundaries)
- _generate_narrative_bullets: singular/plural forms for all activity types
- generate_scorecard: token augmentation max() logic (event vs ledger)
- ScorecardSummary.to_dict: ISO timestamp format, tests_affected count
Fixes#1139
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
