Adapt funding round grid columns on dashboard to match number of rounds

Problem

The applicant dashboard always displayed funding rounds in a fixed 4-column grid. When an organisation had only one, two, or three rounds, the layout looked sparse and unbalanced with empty columns.

How it works

The funding rounds grid on the applicant dashboard now adapts its column count based on how many rounds are available:

Rounds	Layout
1	Single centred column (max 50% width)
2	Two-column grid
3	Three-column grid
4+	Four-column grid (original behaviour)

All layouts remain responsive and collapse to fewer columns on smaller screens. This is a visual improvement only -- no functionality has changed.