design: two-color palette — rename all tokens to --cream / --blue

Replace ochre-clay, carbon-black, burnt-oxide, slate-indigo with clean
two-color system: --cream (#f4f0e8) and --blue (#041cf3). Update every
component, utility class, and test assertion.

src/widgets/Navigation/ui/MobileNav.tsx

@@ -30,13 +30,13 @@ export function MobileNav({ items }: Props) {
   }, [pathname]);
 
   return (
-    <div className="lg:hidden fixed top-0 left-0 right-0 bg-ochre-clay brutal-border-bottom z-50">
+    <div className="lg:hidden fixed top-0 left-0 right-0 bg-cream brutal-border-bottom z-50">
       <div className="px-6 py-4 flex items-center justify-between">
         <h4>allmy.work</h4>
         <button
           type="button"
           onClick={() => setIsOpen((prev) => !prev)}
-          className="brutal-border px-4 py-2 bg-carbon-black text-ochre-clay"
+          className="brutal-border px-4 py-2 bg-blue text-cream"
         >
           {isOpen ? 'Close' : 'Menu'}
         </button>
@@ -44,7 +44,7 @@ export function MobileNav({ items }: Props) {
       {isOpen && (
         <div className="px-6 py-6 brutal-border-top space-y-2 max-h-[80vh] overflow-y-auto">
           {items.map((item) => (
-            <Link key={item.id} href={`/${item.id}`} className="block w-full brutal-border bg-ochre-clay px-4 py-3">
+            <Link key={item.id} href={`/${item.id}`} className="block w-full brutal-border bg-cream px-4 py-3">
               <div className={cn('flex items-baseline gap-3')}>
                 <span className="text-sm opacity-60 font-body">{item.number}</span>
                 <span