Add missing Beartype decorators

[adamtheturtle]

Summary

• Add 12 missing @beartype decorators to typed production functions and concrete classes.
• Keep intentional runtime boundaries such as Protocols, framework callbacks, nested closures, and recursive forward-reference models undecorated.

Validation

• uv run --group dev ruff check .
• uv run --group dev pytest -q
• uv run --group dev prek run --all-files --hook-stage pre-commit
• uv run --group dev prek run --all-files --hook-stage pre-push