Add .clang-tidy to suppress readability-uppercase-literal-suffix in tests/ #181

Context

CodeRabbit repeatedly flags lowercase float-literal suffixes (0.1f, 1.0f, etc.) in test files as triggering readability-uppercase-literal-suffix. The entire codebase consistently uses lowercase f — this is an established project convention.

Proposed Fix

Add a .clang-tidy file that suppresses readability-uppercase-literal-suffix for the tests/ directory, or project-wide if the team prefers.

Why Not Fix Inline

Changing to uppercase F would be inconsistent with every other float literal in the codebase. This is a tooling configuration issue, not a code issue.

Raised by CodeRabbit reviews on PR #179 (rounds 6, 7).