fix: fix SubscriptionPage crash — align with API response structure

API returns { subscription: {...}|null, used_trial: bool } not flat MySubscription.
- Added MySubscriptionData interface with correct nested shape
- Extract my = myRaw.subscription and usedTrial = myRaw.used_trial separately
- Replace my.used_trial references with usedTrial variable

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/admin/types/index.ts

@@ -337,6 +337,18 @@ export interface SubscriptionPeriod {
   is_trial: boolean;
 }
 
+export interface MySubscriptionData {
+  subscription: {
+    plan: { name: string; level: number; features: Record<string, boolean> };
+    period?: { label: string; duration_months: number };
+    is_trial: boolean;
+    starts_at?: number;
+    expires_at?: number | null;
+    days_remaining?: number;
+  } | null;
+  used_trial: boolean;
+}
+/** @deprecated use MySubscriptionData */
 export interface MySubscription {
   plan: { name: string; level: number; features: Record<string, boolean> };
   period?: { label: string; duration_months: number };