Build: Home dashboard components & UI

[CoreyAllenAudio]

Context

Implements the Home screen defined in the design issue (#1). This is the first
screen a user sees after login and the hub for future navigation.

Scope

Build the actual Compose UI and components for Home, following the approved
design from #1. Does NOT include backend/API wiring (see the API layer issue).

Tasks

• Replace the placeholder HomeScreen body with real layout
• Build the primary navigation component(s) from the Design: Home screen layout & navigation model #1 design
• Add dashboard placeholder components (cards/sections)
• Ensure it uses the shared DesksideScaffold + theme
• Verify back navigation still behaves correctly

Acceptance Criteria

• Home renders the designed layout on an emulator
• Navigation elements are present and reachable (even if targets are stubs)
• No regressions in the login → home → back flow

Notes / design

Depends on the layout + navigation model decided in #1.