refactor(design): one drawn check for every checkable row that cannot be an input (E28 S3e3b)

ui/MenuCheck: a box filled with the accent for a set (a minus for a group
only partly in), a bare tick for one choice, in the row's leading slot.
Replaces seven hand-drawn marks: three box sizes, a tinted box, a cross
for "on" in the table filter, a trailing tick in the language menu.

frontend/src/components/ui/SortControl.tsx

@@ -1,5 +1,6 @@
 import { useState, type ReactNode } from "react";
-import { ArrowDown, ArrowUp, Check } from "lucide-react";
+import { ArrowDown, ArrowUp } from "lucide-react";
+import { MenuCheck } from "./MenuCheck";
 import { SelectTrigger } from "./SelectTrigger";
 import { pickSort, type SortOption, type SortState } from "../../lib/columnSort";
 import { PopoverItem, PopoverSurface } from "./AnchoredPopover";
@@ -112,9 +113,7 @@ export default function SortControl({
                 active === null ? "text-fg" : "text-muted"
               }`}
             >
-              <Check
-                className={`h-3.5 w-3.5 shrink-0 ${active === null ? "text-accent" : "opacity-0"}`}
-              />
+              <MenuCheck kind="one" on={active === null} />
               <span className="flex-1 truncate">{defaultLabel}</span>
             </PopoverItem>
           )}
@@ -131,7 +130,7 @@ export default function SortControl({
                   on ? "text-fg" : "text-muted"
                 }`}
               >
-                <Check className={`h-3.5 w-3.5 shrink-0 ${on ? "text-accent" : "opacity-0"}`} />
+                <MenuCheck kind="one" on={on} />
                 <span className="flex-1 truncate">{o.label}</span>
               </PopoverItem>
             );