fix: quote nvchecker section names containing non-bare-key chars

Section names with '.', '-', etc. must be TOML-quoted (e.g. ["yt-dlp"]),
otherwise nvchecker fails to parse them. add_nvchecker_section wrote bare
[pkg] headers, so such names had to be hand-quoted. Worse, _has_nvchecker_section
only matched the bare form, so already-present quoted sections were reported as
missing and re-flagged for populate on every 'mkhint -C' run.

Add _nvchecker_label helper as the single source of truth for the written
label (bare iff name matches ^[A-Za-z0-9_]+$, else double-quoted), used by
both the write side (3 section headers + messages) and the read side
(_has_nvchecker_section grep, with regex metachars escaped so '.' is literal).

Tests T32-T34 cover quoted-header write, no-duplicate on re---new, and
--check recognizing an existing quoted section.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions