Function format_maintainability_text 

pub fn format_maintainability_text(report: &MaintainabilityReport) -> String

Format maintainability index report for text output

Shows per-file MI scores sorted worst-first, with grade distribution summary. Top 30 files shown by default (worst MI first).

Maintainability Index (47 files, avg MI=42.3)

Grade distribution: A=5 B=12 C=18 D=10 F=2

 #   MI  Grade  LOC  AvgCC  File
 1  10.8    F   612   18.2  core.py
 2  22.1    F   445   12.6  parser.py
 3  28.4    D   203    8.1  utils.py