feat: add Eidoverse source selectors

[atomantic]

Summary

• add Self/Upstream and HTTPS/SSH source controls to Eidoverse settings
• preserve the selected Git remote scheme and update installed origins in place
• expose fork-aware source-owner metadata without presenting upstream as the user''s fork
• expand route, service, and rendered interaction coverage

Testing

• server: vitest run services/instanceFeatures.test.js services/eidoverse.test.js routes/settings.test.js (80 passed)
• client: vitest run src/components/settings/InstanceFeaturesTab.test.jsx (15 passed)