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.

internal/models/cv.go

@@ -105,6 +105,7 @@ type Project struct {
 	Location         string   `json:"location"`
 	StartDate        string   `json:"startDate"`
 	Current          bool     `json:"current"`
+	MaintainedBy     string   `json:"maintainedBy,omitempty"` // Optional maintainer name (e.g., "SAP")
 	Technologies     []string `json:"technologies"`
 	ShortDescription string   `json:"shortDescription"`
 	Responsibilities []string `json:"responsibilities"`