fix(ui): wrap detail-page header action buttons on mobile

OfferDetail/OrderDetail/InvoiceDetail/ProjectDetail headers each have a custom action-button row that was flexShrink:0, so (like the alert/PageHeader cases) it stayed at content width and its buttons overflowed/clipped on phones. Dropped flexShrink:0 (and added flexWrap on ProjectDetail which lacked it) so the action row conforms to the available width and the buttons wrap onto multiple lines. Verified on OfferDetail at 430px: buttons span two rows, no container overflow, no page scroll.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/pages/OfferDetail.tsx

@@ -1105,7 +1105,6 @@ export default function OfferDetail() {
               display: "flex",
               alignItems: "center",
               gap: 1,
-              flexShrink: 0,
               flexWrap: "wrap",
             }}
           >