Complete function completes common ANSI escape sequence in completion items

Start by tracing PSReadLine's Complete logic using the supplied Register-ArgumentCompleter reproduction, focusing on how the common prefix is derived from ListItemText. Verify that ANSI escape sequences are not inserted into the completed command arguments, while normal completion text still works as expected.

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest released version
• Search the existing issues, especially the pinned issues.

Exception report

From https://github.com/carapace-sh/carapace/issues/997#issuecomment-3566731943

PSReadLine's `Complete` logic attempts to auto-complete the input with the "common prefix" of all available matches on the first `<TAB>`. While the actual `CompletionText` differ, Carapace prepends the same ANSI escape codes to the `ListItemText` of every entry to ensure styling. The `Complete` function _correctly_ identifies this ANSI sequence as the shared prefix and prints it to the prompt.

Screenshot

Environment data

PS Version: 7.5.4
PS HostName: ConsoleHost (Windows Terminal)
PSReadLine Version: 2.4.5
PSReadLine EditMode: Windows
OS: 10.0.26100.7306 (WinBuild.160101.0800)
BufferWidth: 158
BufferHeight: 25

Steps to reproduce

Set-PSReadLineKeyHandler -Chord Tab -Function Complete
Register-ArgumentCompleter -Native -ScriptBlock {
    param($wordToComplete, $commandAst, $cursorPosition)
    @(
        [System.Management.Automation.CompletionResult]::new("aa", "`e[2maa", [System.Management.Automation.CompletionResultType]::ParameterValue, "1"),
        [System.Management.Automation.CompletionResult]::new("bb", "`e[2mbb", [System.Management.Automation.CompletionResultType]::ParameterValue, "2")
    )
} -CommandName 'bash'

Expected behavior

Completion should not include ANSI escape sequence

Actual behavior

Escape sequence is completed as part of the arguments

bash ^[[2m