chore: add shadcnuikit registry config

Registers the paid @shadcnuikit registry alongside the @ss-* ones. The API key travels as a Bearer header and is read from REGISTRY_TOKEN in .env, which is gitignored; .env.example documents the variable.

.env.example

@@ -2,3 +2,7 @@
 # (npx shadcn add @ss-blocks/...). Mesmos valores do up-track.
 EMAIL=
 LICENSE_KEY=
+
+# Token do shadcnuikit, usado pelo registry @shadcnuikit do components.json
+# (npx shadcn add @shadcnuikit/...). Vai como Bearer no Authorization.
+REGISTRY_TOKEN=

components.json

@@ -39,6 +39,12 @@
         "email": "${EMAIL}",
         "license_key": "${LICENSE_KEY}"
       }
+    },
+    "@shadcnuikit": {
+      "url": "https://shadcnuikit.com/r/{name}.json",
+      "headers": {
+        "Authorization": "Bearer ${REGISTRY_TOKEN}"
+      }
     }
   }
 }