feat: Add certificate templates for Scrum, ITIL, and PRINCE2 courses

- Add 3 new HTML templates: ScrumGeneric, ITIL, PRINCE2
- Add 3 background images: blue (Scrum), green (ITIL), orange (PRINCE2)
- Extract and add signatures: Gablas, Husam
- Update certificate.service.js to support multiple templates with different backgrounds

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/services/ai-kurzy/certificate.service.js

@@ -20,13 +20,26 @@ export const CERTIFICATE_TEMPLATES = {
     name: 'AI Certifikát',
     file: 'AIcertifikat.html',
     description: 'Osvedčenie o absolvovaní AI kurzu',
+    background: 'background.jpeg',
+  },
+  ScrumGeneric: {
+    name: 'Scrum (Gablas)',
+    file: 'ScrumGeneric.html',
+    description: 'Scrum Master / Product Owner - lektor Gablas',
+    background: 'background-blue.jpeg',
+  },
+  ITIL: {
+    name: 'ITIL (Husam)',
+    file: 'ITIL.html',
+    description: 'ITIL Foundation - lektor Husam',
+    background: 'background-green.jpeg',
+  },
+  PRINCE2: {
+    name: 'PRINCE2 (Gablas)',
+    file: 'PRINCE2.html',
+    description: 'PRINCE2 Foundation/Practitioner - lektor Gablas',
+    background: 'background-orange.jpeg',
   },
-  // Add more templates here in the future
-  // participation: {
-  //   name: 'Potvrdenie o účasti',
-  //   file: 'participation.html',
-  //   description: 'Potvrdenie o účasti na školení',
-  // },
 };
 
 /**
@@ -57,9 +70,12 @@ const generateCertificateId = (registraciaId) => {
 /**
  * Load assets as base64 for embedding in HTML
  */
-const loadAssets = async () => {
+const loadAssets = async (templateName) => {
+  const template = CERTIFICATE_TEMPLATES[templateName];
+  const backgroundFile = template?.background || 'background.jpeg';
+
   const [background, signatureGablasova, signatureZdarilek] = await Promise.all([
-    fs.readFile(path.join(ASSETS_DIR, 'background.jpeg')),
+    fs.readFile(path.join(ASSETS_DIR, backgroundFile)),
     fs.readFile(path.join(ASSETS_DIR, 'signature-gablasova.png')),
     fs.readFile(path.join(ASSETS_DIR, 'signature-zdarilek.png')),
   ]);
@@ -196,7 +212,7 @@ export const generateCertificate = async (registraciaId, templateName = 'AIcerti
   // Load template and assets
   const [templateHtml, assets] = await Promise.all([
     loadTemplate(templateName),
-    loadAssets(),
+    loadAssets(templateName),
   ]);
 
   // Generate certificate data