Run Black formatter across 83 files and fix 1514 ruff violations:
- E722: bare except → typed exceptions (17 fixes)
- E711/E712/E721: comparison style fixes with noqa for SQLAlchemy (44 fixes)
- F841: unused variable assignments (70 fixes)
- F541/F401: f-string and import cleanup (1383 auto-fixes)
Remaining 925 errors are all F403/F405 (star imports) — structural,
requires converting to explicit imports in a separate effort.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
