refactor(portal): extract shared partner types and data composables

Move partner domain types out of data/customers.ts into types/partner.ts so the fixture data exports can be removed later without breaking type imports. Add usePartnerTenants / usePartnerMrr composables wrapping the shared-key partner fetches.

apps/portal/components/partner/CustomerTaskPanel.vue

@@ -3,7 +3,7 @@
 // Pre-fills notes from the health drivers and lets the partner tweak before
 // creating the task.
 
-import type { CustomerOrg } from '~/data/customers'
+import type { CustomerOrg } from '~/types/partner'
 
 export interface TaskContext {
   customer: CustomerOrg

apps/portal/components/partner/EnterCustomerConfirmModal.vue

@@ -4,7 +4,7 @@
 // customer org will be logged under their partner identity, and prompts for
 // an optional (but recommended) reason — captured into the customer audit log.
 
-import type { CustomerOrg } from '~/data/customers'
+import type { CustomerOrg } from '~/types/partner'
 
 const props = defineProps<{ customer: CustomerOrg | null }>()
 const emit = defineEmits<{ close: []; confirm: [reason: string] }>()