Integrated onboarding app into main companion navigation and PWA cache

[jharbieh]

Status: done

Completed work:

• Added Member Onboarding entry in sidebar navigation.
• Added onboarding card on dashboard quick actions.
• Added action routing in webapp app.js.
• Updated service worker cache manifest to include onboarding assets.

Outcome:

• Onboarding behaves like a first-class sub app and is available from primary UX flows.