Add 'About' info to Settings: app version and build info

[alimaandev]

Summary

desktop/src/components/settings/SettingsPanel.tsx has an 'About' section (line ~308) that currently shows a Theme label, but no app version/build metadata. The API /api/v1/system-info already returns python_version and related info (api_server.py lines ~454-480).

Goal

Surface app version + Python version in the About section by fetching from /api/v1/system-info.

Tasks

• Fetch system-info in SettingsPanel (or reuse the data already loaded by the app's data layer)
• Render app version, Python version, and host platform in the About section
• Handle the loading and error states gracefully
• Add/extend a Vitest test in desktop/src/test/SettingsPanel.test.tsx

Acceptance criteria

• About section shows version info from the API
• Loading/error states don't crash the panel
• Test covers the new rendering

Labels

good first issue, help wanted