Refactor to multi-category catalog with polished light mode

- Restructure from single filament table to multi-category product catalog
  (filamenti, stampaci, ploce, mlaznice, delovi, oprema)
- Add shared layout components (SiteHeader, SiteFooter, CategoryNav, Breadcrumb)
- Add reusable UI primitives (Badge, Button, Card, Modal, PriceDisplay, EmptyState)
- Add catalog components (CatalogPage, ProductTable, ProductGrid, FilamentCard, ProductCard)
- Add admin dashboard with sidebar navigation and category management
- Add product API endpoints and database migrations
- Add SEO pages (politika-privatnosti, uslovi-koriscenja, robots.txt, sitemap.xml)
- Fix light mode: gradient text contrast, category nav accessibility,
  surface tokens, card shadows, CTA section theming

app/ploce/layout.tsx

@@ -0,0 +1,18 @@
+import type { Metadata } from 'next';
+
+export const metadata: Metadata = {
+  title: 'Bambu Lab Build Plate (Podloga)',
+  description: 'Bambu Lab build plate podloge - Cool Plate, Engineering Plate, High Temp Plate, Textured PEI.',
+  openGraph: {
+    title: 'Bambu Lab Build Plate (Podloga) - Filamenteka',
+    description: 'Bambu Lab build plate podloge - Cool Plate, Engineering Plate, High Temp Plate, Textured PEI.',
+    url: 'https://filamenteka.rs/ploce',
+  },
+  alternates: {
+    canonical: 'https://filamenteka.rs/ploce',
+  },
+};
+
+export default function PloceLayout({ children }: { children: React.ReactNode }) {
+  return <>{children}</>;
+}

app/ploce/page.tsx

@@ -0,0 +1,43 @@
+'use client';
+
+import { SiteHeader } from '@/src/components/layout/SiteHeader';
+import { SiteFooter } from '@/src/components/layout/SiteFooter';
+import { Breadcrumb } from '@/src/components/layout/Breadcrumb';
+import { CatalogPage } from '@/src/components/catalog/CatalogPage';
+import { getCategoryBySlug } from '@/src/config/categories';
+
+export default function PlocePage() {
+  const category = getCategoryBySlug('ploce')!;
+
+  return (
+    <div className="min-h-screen" style={{ background: 'var(--surface-primary)' }}>
+      <SiteHeader currentCategory="ploce" />
+      <main className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-6 sm:py-8">
+        <article>
+          <Breadcrumb items={[
+            { label: 'Pocetna', href: '/' },
+            { label: 'Build Plate (Podloge)' },
+          ]} />
+          <div className="flex items-center gap-3 mt-3 mb-6">
+            <div className="w-1.5 h-8 rounded-full" style={{ backgroundColor: category.colorHex }} />
+            <h1
+              className="text-2xl sm:text-3xl font-black tracking-tight"
+              style={{ fontFamily: 'var(--font-display)', color: 'var(--text-primary)' }}
+            >
+              Bambu Lab Build Plate Podloge
+            </h1>
+          </div>
+          <CatalogPage
+            category={category}
+            seoContent={
+              <p className="text-sm leading-relaxed max-w-3xl" style={{ color: 'var(--text-secondary)' }}>
+                Originalne Bambu Lab build plate podloge za 3D stampanje. Cool Plate, Engineering Plate, High Temp Plate i Textured PEI Plate. Kompatibilne sa A1 Mini, A1, P1S, X1C i drugim modelima. Nove i polovne podloge u privatnoj prodaji.
+              </p>
+            }
+          />
+        </article>
+      </main>
+      <SiteFooter />
+    </div>
+  );
+}