fix(file-tree): keep the folder's click target filling the row beside its action

Moving `rowProps` to the wrapper also took `min-w-full` off the header
button, so an action-bearing folder row shrank its trigger to the label:
clicking anywhere between the name and the ⋯ hit the wrapper, which owns
no click handler and cannot bubble into its sibling button, and the
folder neither selected nor expanded.

`grow` restores the full-width target. Not `flex-1` — its zero basis
would drop the label out of the row's intrinsic width, and this tree
sizes itself to its longest row and scrolls horizontally.

Measured in a browser against the built CSS: the header is 493px of a
525px row (the remaining 32px is the action strip), and the tree's total
content width is unchanged at 537px.