feat(discount): admin Discount Management tab + uuid-based rule targets

Switch rule target references from int ids to uuids (frontend-friendly; the
engine compares uuids directly) via a migration. Add a Discount Management
tab to the subscription page with a full CRUD UI (DiscountTab): table + modal
form with per-type dynamic target fields (tenant tag / service cascade /
amount / visit count / specific patient / occasion + validity window),
priority and combinable/active toggles. Verified TSC + build.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/admin/types/index.ts

@@ -124,6 +124,46 @@ export interface AppointmentEvent {
     created_at: number;
 }
 
+export type DiscountRuleType =
+    | 'patient_tag'
+    | 'invoice_amount'
+    | 'specific_patient'
+    | 'occasion'
+    | 'service'
+    | 'visit_count';
+
+export interface DiscountRule {
+    uuid: string;
+    name: string;
+    type: DiscountRuleType;
+    discount_type: 'percent' | 'fixed';
+    value: number;
+    priority: number;
+    combinable: boolean;
+    active: boolean;
+    valid_from: number | null;
+    valid_to: number | null;
+    target_tag_uuid: string | null;
+    target_record_uuid: string | null;
+    target_service_item_uuid: string | null;
+    min_amount_rials: number | null;
+    min_visit_count: number | null;
+    occasion_kind: string | null;
+    created_at: number;
+    updated_at: number;
+}
+
+export interface DiscountSuggestion {
+    rule_uuid: string;
+    rule_name: string;
+    type: DiscountRuleType;
+    discount_type: 'percent' | 'fixed';
+    value: number;
+    discount_rials: number;
+    combinable: boolean;
+    priority: number;
+}
+
 export type PaymentStatus =
     | "pending"
     | "success"