Add unit tests for the CLI progress-bar renderer (render_progress_bar)

[tsouth89]

Context

render_progress_bar(percent, width, use_color) in rust/src/cli/usage.rs:548 renders an ASCII bar of █/░ inside [...], clamping non-finite/out-of-range input. With use_color = false it is fully deterministic. usage.rs already has a #[cfg(test)] mod tests, so new cases slot right in.

Task

Add unit tests for render_progress_bar in the existing test module.

Acceptance criteria

• With use_color = false: assert exact strings for 0%, 50%, 100% at a fixed width (e.g. 10).
• Assert non-finite input (f64::NAN) renders as empty (0%).
• Assert >100 clamps to full and <0 clamps to empty.
• No ANSI codes asserted for the use_color = false path.

How to test

cargo test --manifest-path rust/Cargo.toml

Pointers

• Function: rust/src/cli/usage.rs:548; existing tests: same file, #[cfg(test)] mod tests.