feat: show error state in admin pages when a query fails

[scldrn]

Context

Several admin panel pages consume React Query hooks but only destructure data and isLoading. When a query fails (network error, Supabase outage, expired token), the page silently renders empty — no feedback to the user whatsoever.

Affected pages

• ruteria/app/(admin)/admin/inventario/page.tsx — useInventarioCentral() ignores error
• ruteria/app/(admin)/admin/productos/page.tsx — useProductos() ignores error
• Inventory tabs (colaboradoras, movimientos, valorizado)

Example

// Current — fails silently
const { data: items = [], isLoading } = useInventarioCentral()

// Correct
const { data: items = [], isLoading, error } = useInventarioCentral()
if (error) return <ErrorMessage error={error} />

Task

1. Create (or reuse if one exists) an <ErrorMessage /> component with a friendly message and a "Retry" button that calls refetch().
2. Add error handling in each affected page following the pattern above.
3. Apply the same pattern to any (campo)/ pages that are also missing it.

Acceptance criteria

• No admin page goes silently blank when its query fails.
• The error component is visually consistent with the design system (navy + amber palette).