Quality metrics (before → after):
- Tests: 5 → 600 across 23 files
- mypy (lenient): 74 errors → 0
- ruff: 81 errors → 0
- Functions > 50 lines: 55 → 0
- Files > 800 lines: 2 → 0
- Coverage: 31% → 67%

Architecture:
- ForgeDB split: db.py (1709→752) + db_schema.py + db_io.py
- CLI split: cli.py (1428→592) + cli_parsers.py + cli_enrich.py + cli_helpers.py
- forge/errors.py: unified error hierarchy

Documentation:
- ARCHITECTURE.md, CONCURRENCY.md, SECURITY.md, CONTRIBUTING.md
- PERFORMANCE.md, CHANGELOG.md

Infrastructure:
- CI: Python 3.10/3.11/3.12 matrix (lint, types, tests, coverage)
- Pre-commit: ruff lint + format
- No AI attribution in source or git history