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/docs/api/page.tsx

@@ -60,7 +60,7 @@ curl -X POST -H "Authorization: Bearer ***" \\
         </p>
         <h3>API key (Bearer token)</h3>
         <p>
-          For server-to-server automation, scripts, and the SDK, use an API key. Generate keys from
+          For server-to-server automation, scripts, and integrations, use an API key. Generate keys from
           <strong> Settings → API Keys</strong>. Keys are bearer tokens — pass them in the <code>Authorization</code>
           header on every request:
         </p>