Module grades 

Comprehensive quality grade system (A-F) for all connection metrics.

Provides letter grades with color support for:

• Ping/Latency
• Jitter
• Download speed
• Upload speed
• Bufferbloat
• Stability (CV%)
• Overall connection quality

Enums

LetterGrade

Letter grade for connection quality.

Functions

format_grade_line

Format a grade line with label, grade, and optional value.

grade_badge

grade_bufferbloat

Grade bufferbloat based on added latency under load.

grade_download

Grade download speed (higher is better).

grade_jitter

Grade jitter value (lower is better).

grade_overall

Compute overall connection grade from individual grades and profile weights.

grade_ping

Grade a ping value (lower is better). Profile-aware thresholds.

grade_stability

Grade stability based on CV% (lower = more stable).

grade_upload

Grade upload speed (higher is better).

score_to_grade

Convert a numeric score (0-100) to a letter grade.