test: pre-commit and type checking

[planetf1]

Context

Part of the Testing Infrastructure & Strategy Overhaul epic (item 10). Subsumes #456 (add pyright check).

Objective

Keep pre-commit fast and reliable. Investigate faster type checkers as alternatives to mypy, and address the venv activation friction.

Work

• Investigate ty or pyright as faster alternatives to mypy (Add pyright check #456)
• Address venv activation friction — pre-commit currently fails if the venv isn't activated; explore whether a faster type checker removes this requirement or whether the hook can handle activation itself
• Ensure pre-commit stays within the <60s budget
• No tests in pre-commit for now (revisit if unit tests become fast enough)
• Update contributor documentation on pre-commit setup

Notes

• Add pyright check #456 (add pyright check) is a sub-issue of this work item
• Pre-commit tier: lint + type checking only, <60s budget