fix(pinterest): add OAuth token refresh handler

Added Pinterest provider to getProviderAuthConfig() to enable automatic
token refresh when access tokens expire. Without this, users would
experience authentication failures after tokens expire.

Configuration:
- Token endpoint: https://api.pinterest.com/v5/oauth/token
- Uses Basic Authentication (as per Pinterest OAuth spec)
- Supports refresh token rotation

This prevents authentication failures and ensures continuous Pinterest
integration functionality.

Author: Shubhamxshah

apps/sim/lib/oauth/oauth.ts

@@ -1081,6 +1081,19 @@ function getProviderAuthConfig(provider: string): ProviderAuthConfig {
         supportsRefreshTokenRotation: false,
       }
     }
+    case 'pinterest': {
+      const { clientId, clientSecret } = getCredentials(
+        env.PINTEREST_CLIENT_ID,
+        env.PINTEREST_CLIENT_SECRET
+      )
+      return {
+        tokenEndpoint: 'https://api.pinterest.com/v5/oauth/token',
+        clientId,
+        clientSecret,
+        useBasicAuth: true,
+        supportsRefreshTokenRotation: true,
+      }
+    }
     default:
       throw new Error(`Unsupported provider: ${provider}`)
   }