fix(scripts): match bash case-sensitivity for acronym retention in PowerShell branch names

[Quratulain-bilal]

closes #3131

what

create-new-feature keeps a short (<3 char) word in the generated branch name only when that word appears in uppercase in the description — the idea is to preserve acronyms like AI or ML while dropping ordinary short words. The code comment says exactly this.

the bash script does the check with a case-sensitive grep:

elif echo "$description" | grep -q "�${word^^}�"; then

but the PowerShell script used -match, which is case-insensitive by default:

} elseif ($Description -match "�$($word.ToUpper())�") {

since the word being tested is itself lowercased earlier, -match against its uppercased form always matches — so on PowerShell every short non-stop word was kept, not just acronyms.

impact

same description, different branch name depending on the shell:

description	bash	powershell (before)
go AI now	001-ai-now	001-go-ai-now
go to the pub	001-pub	001-go-pub

go is a 2-char non-stop word that is lowercase, so it should be dropped (and is, on bash). on PowerShell it leaked into the branch name.

fix

switch -match to -cmatch so the comparison is case-sensitive, matching the bash grep. one-character change plus a clarifying comment.

tests

added parity tests (TestShortWordRetentionBash / ...PowerShell) covering a dropped lowercase short word and a kept uppercase acronym. verified the PowerShell case fails on the pre-fix script (go AI now -> 001-go-ai-now) and passes after.

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note: i used an ai assistant to help investigate and prepare this change. disclosing per CONTRIBUTING.md.