Change a cell's font family

What it does

Pick a font family for the selected cells from the Font dropdown in the toolbar — Default (system-ui), Serif (Georgia), or Mono (Courier New). Font family is presentation, separate from the cell's value: changing the family of =A1+B1 styles the number without touching the formula. It undoes and redoes like any other edit.

Testing note

The manifest scenario runner drives the canvas and keyboard only — it has no verb for clicking a toolbar control — so the family-change interaction is not yet expressible as a runnable scenario. It is verified end-to-end via agent-browser (change the Font select, then assert window.truecalc.store.formatAt('A1').fontFamily) and by colocated unit tests over the control's pure apply/getValue and the render styleContributor. Adding a select verb to the runner would let this feature carry a full runnable scenario like font size does.

Verified behavior

Matches Google Sheets: Font family is a per-cell presentation attribute, independent of the cell's value or formula, that undoes/redoes like any edit. In the Google editors it is chosen from a toolbar Font dropdown (there is no keyboard shortcut); choosing a family applies it to the whole selection, and an unformatted cell renders in the grid's default family until one is chosen.

Selecting an unformatted cell keeps its value (default family)

Given

• A1 = x

When I click A1

Then

• A1 shows x