feat: update references section and fix experience logos in print

References section improvements:
- Remove TwenTIC recommendation letter
- Add Megabanner recommendations with author attribution (David Amorós)
- Update Presentation Letter URL to Domestika profile
- Update Chronological CV link to trigger PDF download modal
- Add 'action' field to Reference struct for custom behaviors

Print layout fixes:
- Show experience company logos in print view (40×40px)
- Remove print media query that was hiding .company-logo elements
- Maintain consistency with other logo types (courses, projects, awards)

Technical changes:
- Add Action field to Reference model with omitempty JSON tag
- Implement conditional rendering for downloadPDF action in template
- Links with action="downloadPDF" now call openPdfModal() function

templates/cv-content.html

@@ -330,7 +330,7 @@
                     </summary>
                 {{range .CV.References}}
                 <div class="reference-item">
-                    {{if .TextBefore}}{{.TextBefore}} {{end}}<a href="{{.URL}}" target="_blank" rel="noopener noreferrer"><strong>{{if .LinkText}}{{.LinkText}}{{else}}{{.Title}}{{end}}</strong></a>{{if .TextAfter}} {{.TextAfter}}{{end}}
+                    {{if .TextBefore}}{{.TextBefore}} {{end}}{{if eq .Action "downloadPDF"}}<a href="{{.URL}}" onclick="event.preventDefault(); openPdfModal(); return false;"><strong>{{if .LinkText}}{{.LinkText}}{{else}}{{.Title}}{{end}}</strong></a>{{else}}<a href="{{.URL}}" target="_blank" rel="noopener noreferrer"><strong>{{if .LinkText}}{{.LinkText}}{{else}}{{.Title}}{{end}}</strong></a>{{end}}{{if .TextAfter}} {{.TextAfter}}{{end}}
                 </div>
                 {{end}}
                 </details>