Adjust breaking change workflow based on issues seen

[ericstj]

1. Agent is sometimes ignoring the result of the version calculation script - make it more clear how to handle results.
2. Comment was duplicating issue body. Remove this.
3. Tag the PR's assignees to get attention.

[Copilot]

Pull request overview

Updates the breaking-change-doc skill workflow instructions and helper script to reduce version-detection ambiguity, avoid duplicating the full issue draft in PR comments, and notify PR assignees via @mentions.

Changes:

• Expanded Step 1 metadata collection to include PR assignees and clarified Step 2 version-script handling/logging.
• Updated the PR comment generation workflow to pass assignees for @-mentions and to keep PR comments brief (no inline issue body).
• Enhanced Build-IssueComment.ps1 to accept an -Assignees parameter and emit URL-length diagnostics.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
.github/skills/breaking-change-doc/SKILL.md	Clarifies workflow steps (version detection output handling, assignee metadata, brief PR comment intent).
.github/skills/breaking-change-doc/Build-IssueComment.ps1	Generates a shorter PR comment and supports notifying PR assignees via a new -Assignees parameter.

[Copilot]

$Assignees.Trim() will throw if the caller passes $null (PowerShell parameters can be explicitly set to null). Consider using [string]::IsNullOrWhiteSpace($Assignees) (and trimming once) so the script is robust when there are no PR assignees or the metadata value is missing.

Suggested change

	if ($Assignees.Trim()) {
	$mentionLine = "`n`n/cc $($Assignees.Trim())"
	$trimmedAssignees = ""
	if (-not [string]::IsNullOrWhiteSpace($Assignees)) {
	$trimmedAssignees = $Assignees.Trim()
	$mentionLine = "`n`n/cc $trimmedAssignees"

[Copilot]

Step 2 has conflicting guidance: it says to fall back to manual tag detection when the JSON contains an Error field, but then unconditionally says to use EstimatedVersion anyway. That unconditional line can cause the workflow to ignore the error case; consider removing it or rewording it to apply only when Error is absent.

Suggested change

	Use `EstimatedVersion` as the version for the breaking change issue.
	Only use `EstimatedVersion` as the version for the breaking change issue when
	the JSON does **not** contain an `Error` field.