style(mui): DataTable bold-cell option; restore SPZ/Aktualni-km emphasis + mono Menlo fallback

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

src/admin/pages/Vehicles.tsx

@@ -230,7 +230,7 @@ export default function Vehicles() {
   }
 
   const columns: DataColumn<Vehicle>[] = [
-    { key: "spz", header: "SPZ", mono: true, render: (v) => v.spz },
+    { key: "spz", header: "SPZ", mono: true, bold: true, render: (v) => v.spz },
     { key: "name", header: "Název", render: (v) => v.name },
     {
       key: "brand",
@@ -250,6 +250,7 @@ export default function Vehicles() {
       header: "Aktuální km",
       align: "right",
       mono: true,
+      bold: true,
       render: (v) => `${formatKm(v.current_km)} km`,
     },
     {

src/admin/ui/DataTable.tsx

@@ -12,6 +12,8 @@ export interface DataColumn<T> {
   align?: "left" | "right";
   /** Render the cell with the DM Mono numeric face. */
   mono?: boolean;
+  /** Emphasize the cell (font-weight 500). */
+  bold?: boolean;
   render: (row: T) => ReactNode;
 }
 
@@ -67,7 +69,10 @@ export default function DataTable<T>({
                   align={c.align}
                   sx={{
                     fontSize: ".8rem",
-                    ...(c.mono ? { fontFamily: "'DM Mono', monospace" } : {}),
+                    ...(c.bold ? { fontWeight: 500 } : {}),
+                    ...(c.mono
+                      ? { fontFamily: "'DM Mono', Menlo, monospace" }
+                      : {}),
                   }}
                 >
                   {c.render(row)}