Add admin scoring rule editor

[adrunkhuman]

Summary

• Show active-season scoring rules in the unified admin panel.
• Add a Scoring Rules modal for updating exact/outcome/wrong/late point values.
• Guard stale modal submissions, non-owner/admin submissions, invalid values, and already-scored seasons.

Verification

• uv run pytest --tb=short
• uv run ruff check .
• uv run ruff format --check .
• uv run ty check typer_bot

Closes #220