fix: preserve fractional TPS values

[dajiaohuang]

Update TPS formatting to round values to the nearest tenth, preserving fractional tick rates such as 18.5 while retaining the existing 20.0 cap and over-limit marker.
Fixes #67

Validation:

• Hermetic arithmetic regression check for 18.5, 18.54, 18.55, and over-20.0 capping
• git diff --check
• gradlew test could not start because the host Java 26 runtime is incompatible with Gradle 8.7/Groovy (class file major version 70)