Fix dropdown trigger forcing full width and wrapping in toolbars

The DropDownMenu trigger wrapper was changed to width: 100% in #4581
(CollapsibleOnMobile work) so a header dropdown could fill a sidebar
drawer on mobile. That blanket change made every dropdown trigger
stretch to fill its container, so the ellipsis ("more actions") button
in the Tendril draft/review action footers expanded to full width and
wrapped onto its own line inside the horizontal wrap layout.

Use maxWidth: 100% instead of width: 100% so the trigger sizes to its
content by default (no more spurious wrapping) while still being
constrained to its container. Consumers that want a full-width trigger
can still set the width on the trigger button itself. minWidth: 0 is
kept for flex-shrink safety.

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

Author: dcrjodle

src/frontend/src/widgets/dropDownMenu/DropDownMenuWidget.tsx

@@ -208,7 +208,7 @@ export const DropDownMenuWidget: React.FC<DropDownMenuWidgetProps> = ({
   return (
     <DropdownMenu open={open} onOpenChange={handleOpenChange}>
       <DropdownMenuTrigger ref={triggerRef} asChild>
-        <div style={{ width: "100%", minWidth: 0 }}>{slots.Trigger}</div>
+        <div style={{ maxWidth: "100%", minWidth: 0 }}>{slots.Trigger}</div>
       </DropdownMenuTrigger>
       <DropdownMenuContent
         onClick={(e) => e.stopPropagation()}