fix: remove remaining false SDK claims from features, docs/premium, docs/api (M-2)

- features.tsx: 'JavaScript SDK & REST API' → 'REST API (260+ endpoints)'
- docs/premium: 'the JS SDK' → 'the REST API'
- docs/api: 'and the SDK' → 'and integrations'

The SDK package doesn't exist; the REST API is the correct integration surface.
Deployed to live dashcaddy.net via cPanel API with cache-busting rewrite.

src/app/features/page.tsx

@@ -361,7 +361,7 @@ export default function FeaturesPage() {
                   'Security Center',
                   'One-click backup & restore',
                   'AI Intent Router + MCP Server',
-                  'JavaScript SDK & REST API',
+                  'REST API (260+ endpoints)',
                   'Plugin / Extension system',
                   'i18n (5 languages, RTL)',
                   'Prometheus metrics export',