feat: show version and a safe support summary in Settings

[Abhash-Chakraborty]

Problem

The Settings dashboard reports the runtime profile and worker state, but users cannot quickly confirm the Find application version or copy a small non-secret support summary.

Acceptance criteria

• Add an About card to Settings showing app version, build profile, applied AI mode, and worker health.
• Source the version from the existing backend package version; do not duplicate a hard-coded frontend value.
• Add a Copy support summary button that excludes environment values, paths, media metadata, credentials, and identifiers.
• Provide clear accessible labels and a copied/error status message.
• Add component tests for rendered values, clipboard success, and clipboard failure.
• Update the Settings documentation screenshot/text if needed.

Contributor notes

This is intentionally smaller than the diagnostics-bundle work in #347; it is a short, human-readable summary only.