TASK: Fix unused imports — clippy zero warnings

What

Fix unused imports in trios-git and trios-gb crates so cargo clippy -- -D warnings passes cleanly.

Steps

cargo clippy -p trios-git -- -D warnings 2>&1
cargo clippy -p trios-gb -- -D warnings 2>&1
# Fix every reported unused import / dead_code
cargo clippy --workspace -- -D warnings
# Must be 0 warnings

Law L3 + L4

• L1: Closes #9
• clippy zero warnings is a hard requirement before any feature work

Success

• cargo clippy --workspace -- -D warnings = 0
• cargo test --workspace still green

git commit -m "chore: fix unused imports, clippy --workspace -D warnings = 0\n\nCloses #9"

GO.