Add ort-release-notes skill to draft release notes (#31614)
### Description
<!-- Describe your changes. -->
Add an `ort-release-notes` skill with preset configuration, scoped path
support, and a concise workflow for metadata generation and draft
output.
Also include a lightweight docs entry point and WebGPU EP scoped paths
file.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
Make it easier for AI to generate release note drafts.
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Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Copilot-Session: 3611670d-4e92-4183-8e0e-b2cb659ab624
