Links should throw warning/error on invalid character

Prerequisites

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

Steps to reproduce

Imagine the following function:

Function Get-Test {
    <#
    .SYNOPSIS
        Outputs a greeting message.

    .DESCRIPTION
        This function outputs a greeting message.
    
    .PARAMETER Name
        The name of the person to greet.
    
    .EXAMPLE
        Get-Test -Name "World"
    .NOTES
        Additional information about the function
    .LINK
        - https://example.com/documentation        
    #>
    [CmdletBinding()]
    param (
        [Parameter(Mandatory = $true)]
        [string]$Name
    )

    Write-Output "Hello, $Name! This is a test function."
}

Creating a CommandHelp object using New-CommandHelp is allowed. The export command also successfully exports the result. Trying to import the file, throws an error: No metadata found in Get-Test.md

The reason is because how the HelpUri is added to the metadata:

---
document type: cmdlet
external help file: Get-Test-Help.xml
HelpUri: >-
  https://example.com/documentation


  -
Locale: en-US
Module Name: ''
ms.date: 07/14/2025
PlatyPS schema version: 2024-05-01
title: Get-Test
---

Expected behavior

Able to import the command help after generation.

Actual behavior

An error occurs.

Error details

Environment data

Name                           Value
----                           -----
PSVersion                      7.5.2
PSEdition                      Core
GitCommitId                    7.5.2
OS                             Microsoft Windows 10.0.26100
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

Version

1.0.0-preview5

Visuals

No response

Start by reproducing the issue with New-CommandHelp using the Get-Test example, then trace how the .LINK value becomes HelpUri in the generated Get-Test.md and how import reads its metadata. Done means the generated help can be imported successfully and invalid link characters produce an appropriate warning or error.