feat: add course logo support with servoy, forem, and camaracomercio logos

- Add courseLogo field to Course struct in Go
- Update template to display course logos with fallback to school icon
- Add CSS styling for course logo images (80x80px, contained, bordered)
- Add logos to three courses in both English and Spanish:
  * Servoy World 2011 (servoy.png)
  * Train the Trainers / Formador de Formadores (forem.png)
  * Windows 2003 Server (camaracomercio.png)
- Course logos stored in /static/images/courses/ folder
- Similar implementation to project logos with error handling

data/cv-es.json

@@ -672,6 +672,7 @@
     {
       "title": "Servoy World 2011",
       "institution": "Servoy",
+      "courseLogo": "servoy.png",
       "location": "Amsterdam",
       "date": "2011-02",
       "duration": "3 días",
@@ -685,6 +686,7 @@
     {
       "title": "Formador de Formadores",
       "institution": "FOREM Extremadura",
+      "courseLogo": "forem.png",
       "location": "Cáceres",
       "date": "2009-06",
       "duration": "150 horas",
@@ -698,6 +700,7 @@
     {
       "title": "Windows 2003 Server",
       "institution": "Cámara de Comercio de Cáceres",
+      "courseLogo": "camaracomercio.png",
       "location": "Cáceres",
       "date": "2006-01",
       "duration": "80 horas",