docs: Rename PDF length parameter from 'detailed' to 'short'

Changed PDF export naming convention from 'detailed' to 'short' for better clarity and contrast with 'extended'. Updated:

- Documentation: All references from 'detailed' → 'short'
- JSON data files: Static PDF URLs now use cv-short-jamr-{{YEAR}}-{lang}.pdf
- Frontend modal: Removed 'short' → 'detailed' mapping (now stays as 'short')
- Static PDFs: Renamed cv-detailed-* to cv-short-* (deleted old files)
- Backend validation: Change

data/cv-es.json

@@ -907,7 +907,7 @@
     },
     {
       "title": "Descargar este currículum en Español",
-      "url": "https://juan.andres.morenorub.io/static/pdf/cv-detailed-jamr-{{YEAR}}-es.pdf",
+      "url": "https://juan.andres.morenorub.io/static/pdf/cv-short-jamr-{{YEAR}}-es.pdf",
       "type": "cv",
       "textBefore": "Descargar este currículum en",
       "linkText": "Español"