Keep sparse dashboard card groups compact and center incomplete rows

For dashboard card groups whose item count varies, keep card width and height consistent across populated and empty states. A wrapping flex row with a fixed breakpoint width for each card and centered justification keeps incomplete rows balanced; removing count-specific row spans and viewport-height minimums avoids a single empty card becoming a giant panel. Verify the generated CSS and card rectangles at target widths, including a one-card state. This applies to compact navigation cards; dense tables and intentional featured cards may need different layouts.