[Test] Add Manifest Room route with discrepancy panel

[iamasx]

Summary

Add a manifest-room route that presents manifest groups, package summaries, and a compact discrepancy panel.

Scope

• Add a dedicated manifest-room route.
• Create mock manifest, package, and discrepancy data.
• Build manifest groups, summary cards, and a discrepancy panel.
• Aim for roughly 400-500 changed lines overall, staying reasonably close to that range.

Acceptance Criteria

• The route renders grouped manifest content.
• Package summaries and discrepancy details are visible.
• The route works across standard breakpoints.
• Tests cover the main route content.
• Final PR diff is roughly 400-500 changed lines.

[iamasx]

Implementation plan:

• Add the manifest-room route shell and supporting mock data.
• Build manifest grouping, package summary, and discrepancy components.
• Compose the page with a clear layout and responsive arrangement.
• Add styling refinements and representative tests.
• Run local checks and keep the final diff near the 400-500 line target.