Fix an assert when trimming utf8 strings

[kryksyh]

If a string contains unicode characters with value >= 0x80, it become negative int ch, calling std::isspace with negative argument causes an assert.

Resolves: an assert in audacity during opening VST view if it contains unicode characters

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Build configuration

audacity: audacity/audacity/master
audacity platforms: linux_x64
musescore: musescore/MuseScore/main
musescore platforms: linux_x64

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ℹ️ Recent review info

⚙️ Run configuration

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Review profile: ASSERTIVE

Plan: Advanced

Run ID: d69c810b-6649-4b4b-8a09-4bb5c3dc2f05

📥 Commits

Reviewing files that changed from the base of the PR and between 6798dda and ddbee96.

📒 Files selected for processing (1)

• framework/global/stringutils.cpp

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📝 Walkthrough

Walkthrough

muse::strings::ltrim and rtrim now use find_first_not_of and find_last_not_of with the fixed ASCII whitespace set " \t\n\v\f\r". The previous locale-dependent std::isspace checks were removed.

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to ddbee

Trimming now handles UTF-8 text without asserting on non-ASCII bytes while preserving ASCII whitespace trimming. No concrete merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly describes the primary change: fixing an assertion during UTF-8 string trimming.
Description check	✅ Passed	The description explains the assertion cause, affected scenario, motivation, checklist status, and build configuration. The Resolves: line does not contain a valid issue number or direct issue link,…

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