Function Table

<Table> — fixed-width header + horizontal divider + data rows.

Layout:

1. Sum the explicit width values plus (n-1) * COL_GAP.
2. The remaining space (parent width minus that sum) is split equally among columns without a width (flex columns).
3. Each cell is padded / truncated to its final width before rendering, so layout never depends on the parent applying truncation.

Cell content is plain strings only in v1 — column.render returns a string. ANSI styling within cells is deferred to v2; for now, style at the row level by wrapping

Returns Element