feat(miniapp): add admin billing settings foundation

packages/application/src/household-onboarding-service.test.ts

@@ -150,6 +150,46 @@ function createRepositoryStub() {
             preferredLocale: locale
           }
         : null
+    },
+    async getHouseholdBillingSettings(householdId) {
+      return {
+        householdId,
+        rentAmountMinor: null,
+        rentCurrency: 'USD',
+        rentDueDay: 20,
+        rentWarningDay: 17,
+        utilitiesDueDay: 4,
+        utilitiesReminderDay: 3,
+        timezone: 'Asia/Tbilisi'
+      }
+    },
+    async updateHouseholdBillingSettings(input) {
+      return {
+        householdId: input.householdId,
+        rentAmountMinor: input.rentAmountMinor ?? null,
+        rentCurrency: input.rentCurrency ?? 'USD',
+        rentDueDay: input.rentDueDay ?? 20,
+        rentWarningDay: input.rentWarningDay ?? 17,
+        utilitiesDueDay: input.utilitiesDueDay ?? 4,
+        utilitiesReminderDay: input.utilitiesReminderDay ?? 3,
+        timezone: input.timezone ?? 'Asia/Tbilisi'
+      }
+    },
+    async listHouseholdUtilityCategories() {
+      return []
+    },
+    async upsertHouseholdUtilityCategory(input) {
+      return {
+        id: input.slug ?? 'utility-category-1',
+        householdId: input.householdId,
+        slug: input.slug ?? 'custom',
+        name: input.name,
+        sortOrder: input.sortOrder,
+        isActive: input.isActive
+      }
+    },
+    async promoteHouseholdAdmin() {
+      return null
     }
   }