Python 3.8 compatibility part 2: builtin generics -> typing generics ...

dict[str, X] / list[X] / tuple[X, Y] replaced with Dict/List/Tuple
across backend (main, oauth, scoring). Scoring tests pass.

Python 3.8 compatibility: X | None -> Optional[X] ...

Internal proxy VPS (deploy target) runs Ubuntu 20.04 / Python 3.8.
Replaced PEP 604 unions with typing.Optional across backend
(db, main, oauth, scoring, signing). Scoring tests still pass.

VerIQ v1 MVP: FastAPI backend, 40-task bank, frontend, Ed25519 signing ...

- backend: main.py (API + sessions + rate limit), scoring.py (weighted
  z-score normalization, sanity checks), signing.py (Ed25519 canonical
  payload signing), db.py (SQLite WAL, results + events)
- content: questions.json v1.0.0 (40 original tasks, 4 categories,
  SVG figures), calibration.json placeholder
- frontend: brutalist dark theme, test engine with timer/resume,
  result page with share links, public verify page
- docs: SPEC.md (product + tech spec, milestones)
- smoke-tested: full cycle start->finish->verify, tamper rejection OK