Use Type Annotations or Not

Make a decision to either:
1. Use type annotations across the board
2. Only use them where the compiler complains

And stick with that convention

The issue names no files, tests, or entry points. Begin by reviewing the Rust codebase to measure its current use of type annotations, then establish which convention the project should follow. Done means the convention is decided and applied consistently across the relevant code.

Written by the indexing model from the issue text.