feat(vulnerability): improve GitHub advisory PR body notes with summary, GHSA ID and references

[Churro]

Changes

• Align the GitHub Dependabot vulnerability alert PR body notes with the format used by osvVulnerabilityAlerts
• Add ghsa_id and summary fields to the GitHub SecurityAdvisory schema
• Render advisory notes in a structured, collapsible format with attribution

Note: summary note ghsa_id are required per 2022-11-28 spec.

Context

Please select one of the following:

• This closes an existing Issue, Closes: #

• This doesn't close an Issue, but I accept the risk that this PR may be closed if maintainers disagree with its opening or implementation

• feat(vulnerability): add severity and CVSS details to GitHub Dependabot alerts #42568

AI assistance disclosure

Did you use AI tools to create any part of this pull request?

Please select one option and, if yes, briefly describe how AI was used (e.g., code, tests, docs) and which tool(s) you used.

• No — I did not use AI for this contribution.
• Yes — minimal assistance (e.g., IDE autocomplete, small code completions, grammar fixes).
• Yes — substantive assistance (AI-generated non‑trivial portions of code, tests, or documentation).
• Yes — other (please describe):

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests, but ran on a real repository, or
• Both unit tests + ran on a real repository

The public repository:

• Before: chore(deps): update dependency vite to v8.0.5 [security] (main) #42437
• After: Update dependency vite to v8.0.5 [SECURITY] renovate-demo/github-alerts-vite#1