refactor(login): update interface preference from 'swift' to 'cortex'

- Changed default interface preference in LoginForm component from 'klassiek' to 'cortex'.
- Updated redirect path logic to reflect the new 'cortex' preference.
- Modified button label and state management to align with the new interface preference terminology.
- Adjusted type definition for InterfacePreference to include 'cortex' instead of 'swift'.

lib/auth/client.ts

@@ -270,10 +270,10 @@ export async function getDemoAccessLevel(): Promise<'read_only' | 'interactive'
 }
 
 /**
- * Update user's preferred interface (Swift or Klassiek)
+ * Update user's preferred interface (Cortex or Klassiek)
  * Stored in user_metadata.preferred_interface
  */
-export type InterfacePreference = 'swift' | 'klassiek'
+export type InterfacePreference = 'cortex' | 'klassiek'
 
 export async function updateInterfacePreference(preference: InterfacePreference) {
   const supabase = createClient()