feat: add "Maintained by SAP" badge to CDC Starter Kit project

Added visual badge to show CDC Starter Kit is now maintained by SAP:

1. Go struct changes:
   - Added MaintainedBy field to Project struct (cv.go:108)

2. Data updates:
   - Added "maintainedBy": "SAP" to CDC Starter Kit in cv-en.json
   - Added "maintainedBy": "SAP" to CDC Starter Kit in cv-es.json

3. Template changes:
   - Added maintained-badge display in project header (cv-content.html:226-228)
   - Shows "MAINTAINED BY SAP" (EN) or "MANTENIDO POR SAP" (ES)

4. CSS styling:
   - Added .maintained-badge style with blue background (#3498db)
   - Matches current-badge and expired-badge styling

Badge appears next to project title to highlight SAP's ongoing maintenance.

data/cv-es.json

@@ -788,6 +788,7 @@
       "location": "Online",
       "startDate": "2018",
       "current": false,
+      "maintainedBy": "SAP",
       "technologies": ["SAP CDC", "JavaScript", "React", "Integración de APIs", "Autenticación"],
       "shortDescription": "Demostración completa y kit de inicio para SAP Customer Data Cloud. Proyecto de implementación completa creado 100% de forma independiente como recurso público en GitHub. Ahora mantenido por SAP.",
       "responsibilities": [