Enhance quality report with CD support and diagnostics

[donboyd5]

PR: Enhance quality report with CD support and diagnostics

This is PR 3 of 4 adding congressional district (CD) weighting to TMD.
Based on PRs 1-2 (now merged). See PR #470 for the full roadmap.

Summary

Major expansion of quality_report.py with new diagnostic sections and CD scope support. No solver or target changes.

New features

• --output flag: Save report to file (auto-generated filename in weight directory, or specify a path)
• --scope cds: Full CD support — auto-discovers areas from log files instead of requiring a hardcoded state list
• Scope/timestamp header: Shows scope label, generation time, cumulative and wall-clock solve time
• Aggregate multiplier distribution table: Combined distribution across all area-record pairs
• Weight distribution by AGI stub: National vs sum-of-areas returns and AGI per bin, with percent change
• Diff columns: All comparison tables now show dollar differences alongside percent differences
• Per-bin distortion analysis: Checks a curated set of 16 variables × all AGI bins, marks T (targeted) vs U (untargeted), sorted by distortion, shows top 30 out of N combinations
• Top-N per-area detail: Shows all areas for states (<=60), top 20 by violations/wRMSE for CDs/counties
• Human-readable labels: Converts internal target labels to readable form

Files changed (1 file, +728 / -74)

File	Change
tmd/areas/quality_report.py	All changes above

Test plan

make format                                                # no changes
make lint                                                  # passes clean
python -m tmd.areas.quality_report --scope states          # terminal output
python -m tmd.areas.quality_report --scope states --output # saves to file

The quality report reads existing log and weight files — no solving needed. CD scope (--scope cds) will work after PR 4 implements generation of CD weight files and the user solves for those weights.

Prepared by @donboyd5 and Claude Code