qmlformat 6.11.2 recursed without bound, and segfaulted, on regular
expression literals wider than MaxColumnWidth. Build the roster test's
long warning filter from strings, reuse qprocessFilter() for its
duplicate, and match the smoke harness's private texts as substrings.
Every QML file now formats at a MaxColumnWidth of 100 or more.

Adoption stays blocked on readability: unwrapped output joins
expressions into lines up to 2570 characters, and every wrap width
splits comparisons across lines. TODO.md and docs/development.md
record the new measurements and QTBUG-131686, and the guide now names
the Qt 6 binary, since Qt 5's qmlformat can come first on PATH.

No user-visible change, so no changelog entry.

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>