Enable disabled navigation features (Phases, Analytics pages)

[kivo360]

Problem

Two major navigation items are commented out in the sidebar (frontend/components/sidebar/icon-rail.tsx):

// TODO: Re-enable when phases feature is ready
// { id: "phases", label: "Phases", icon: Workflow, href: "/phases" },

// TODO: Re-enable when analytics feature is ready
// { id: "analytics", label: "Analytics", icon: BarChart3, href: "/analytics" },

The pages exist in the app router but are disabled in navigation.

What needs to happen

1. Review if the Phases page is functional enough to enable
2. Review if the Analytics page has working visualizations
3. Enable the nav items once the underlying pages are ready
4. If pages need work, create sub-issues for each

Difficulty: Depends on page readiness | Skill: Frontend (Next.js/React)