fix(ui): stretch NameBar in folder view flex column

[cqnykamp]

Problem

In the folder view page, the NameBar (gray title bar) collapsed to the width of its text instead of stretching to fill its row like it does on the editor page.

Fix

NameBar.tsx already set width: 100%, which stretched it inside the editor's <HStack> but not inside the folder view's <Flex flexDirection={{ base: "column", md: "row" }}> (parent doesn't constrain a definite width on the cross axis when its own width is content-driven). Added flex={1} to the outer Box (both read-only and editable branches) and the inner Editable so it fills available row/column space in both flex contexts.

Test plan

• Existing NameBar.cy.tsx component tests still pass (15/15)
• Visual check in folder view: NameBar fills the row
• Visual check in editor: NameBar still looks right (no regression)

Note: I couldn't perform the visual checks in this sandbox — the dev MySQL container wasn't reachable from here, so I couldn't bring up the dev server. The change is minimal and isolated to one component; a quick local spin-up should confirm.