fix(composer): normalize Claude NBSP padding in the shared verdict

[haroarthur]

Intent

This contribution consolidates, rather than supersedes, #2029. Claude renders its empty composer as ❯ followed by U+00A0. POSIX [:space:] does not trim that byte, so the shared composer classifier can misread an idle composer as pending on tmux, Herdr, Orca, and bordered cmux. Normalize only the observed U+00A0 at the shared verdict boundary, preserving real-text and dead-shell verdicts.

The false pending verdict caused a measured 10h31m away-mode wedge. The incident chronology belongs here rather than in regression-test comments.

What Changed

• Normalize U+00A0 in both content and plain_content before the existing trim.
• Preserve Kun's cmux U+00A0 special case from fix(cmux): classify borderless Claude composers #2029 unchanged.
• Add focused LC_ALL=C regressions for idle NBSP padding, a real draft after the pad, isolated ZWJ content, plain-content fallback, dead-shell safety, and one Herdr incident fixture.
• Avoid whole-Zs folding, zero-width deletion, arrays, global scratch state, and new public wrappers.

Validation

Raised through no-mistakes (cross-fork). The change and its focused regression tests are clean. The mandatory checks - the full test suite and the pinned ShellCheck 0.11.0 lint - run on this repository's CI and are the authoritative gate. They have not executed yet: the workflow is pending maintainer approval. The required checks are therefore not yet green; they run once approved. (Correcting an earlier draft that implied full validation had completed - it had not.)

Pipeline

Updates from git push no-mistakes

[haroarthur]

Closing as superseded by #2102, which is merged and fully fixes the ❯ + U+00A0 idle-composer misclassification (normalizing all Unicode whitespace before the shared verdict, with a cross-backend matrix test). This branch is now based on #2102's merge commit and no longer carries the fix. Thanks!