fix: revalidate /customize (not /settings) after customize-panel mutations

The invites/onboarding/areas/roles/tiers admin panels moved to /customize, but
their actions still revalidated the old /settings route, so the /customize
Router Cache went stale after a write. Point them at /customize (keeping the
other cross-page revalidations).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/actions/onboarding.ts

@@ -56,7 +56,7 @@ export async function createOnboardingStep(input: {
     .single()
 
   if (error) return { error: error.message }
-  revalidatePath('/settings')
+  revalidatePath('/customize')
   return { id: data.id }
 }
 
@@ -93,7 +93,7 @@ export async function updateOnboardingStep(stepId: string, updates: {
     .eq('space_id', member.space_id)
 
   if (error) return { error: error.message }
-  revalidatePath('/settings')
+  revalidatePath('/customize')
   return { success: true as const }
 }
 
@@ -115,7 +115,7 @@ export async function deleteOnboardingStep(stepId: string) {
 
   if (error) return { error: error.message }
   if (count === 0) return { error: 'Built-in steps cannot be deleted. Disable it instead.' }
-  revalidatePath('/settings')
+  revalidatePath('/customize')
   return { success: true as const }
 }