fix: qflist filepath on windows

[corybsa]

The parse_line function in lua/99/ops/qfix-helpers.lua splits path/line/column by matching the first : separators. On Windows paths like C:\repo\file.lua:10:3,1,note, this causes filename to become only C (drive letter), which breaks quickfix entries.

Edit: just wanted to add some visuals in case anybody was curious what it looks like in Windows:
Before this PR:

After this PR:

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Note

Low Risk
Small, well-scoped parsing change with added test coverage; main risk is stricter numeric matching rejecting previously-accepted malformed inputs.

Overview
Fixes QFixHelpers.parse_line to only treat numeric lnum/col segments as the :/, separators, preventing Windows drive letters (e.g. C:\...) from being mis-parsed as the filename.

Adds a unit test covering Windows drive-letter paths to ensure quickfix entries are created with the full filepath and correct line/column values.

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