chore: Fix Clippy warnings in zkml crate

[mascharkh]

Current State

CI reports 319 Clippy warnings in zkml/. All are code style issues (non-blocking).

Desired State

Zero Clippy warnings when running cargo clippy --lib -p zkml.

Actions

1. Run cargo clippy --fix --lib -p zkml --allow-dirty
2. Manually review and fix any warnings not auto-fixed
3. Ensure tests still pass after changes

Success Criteria

• cargo clippy --lib -p zkml -- -D warnings exits with code 0
• All existing tests pass