feat(subscriptions): migrate subscription management to merchant level and seed tiers

Move subscription create/edit from store detail (broken endpoint) to merchant
detail page with proper modal UI. Seed 4 subscription tiers (Essential,
Professional, Business, Enterprise) in init_production.py. Also includes
cross-module dependency declarations, store domain platform_id migration,
platform context middleware, CMS route fixes, and migration backups.

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

app/modules/tenancy/static/admin/js/store-detail.js

@@ -19,7 +19,6 @@ function adminStoreDetail() {
         loading: false,
         error: null,
         storeCode: null,
-        showSubscriptionModal: false,
 
         // Initialize
         async init() {
@@ -150,39 +149,6 @@ function adminStoreDetail() {
             return 'bg-green-500';
         },
 
-        // Create a new subscription for this store
-        async createSubscription() {
-            if (!this.store?.id) {
-                Utils.showToast(I18n.t('tenancy.messages.no_store_loaded'), 'error');
-                return;
-            }
-
-            detailLog.info('Creating subscription for store:', this.store.id);
-
-            try {
-                // Create a trial subscription with default tier
-                const url = `/admin/subscriptions/${this.store.id}`;
-                const data = {
-                    tier: 'essential',
-                    status: 'trial',
-                    trial_days: 14,
-                    is_annual: false
-                };
-
-                window.LogConfig.logApiCall('POST', url, data, 'request');
-                const response = await apiClient.post(url, data);
-                window.LogConfig.logApiCall('POST', url, response, 'response');
-
-                this.subscription = response;
-                Utils.showToast(I18n.t('tenancy.messages.subscription_created_successfully'), 'success');
-                detailLog.info('Subscription created:', this.subscription);
-
-            } catch (error) {
-                window.LogConfig.logError(error, 'Create Subscription');
-                Utils.showToast(error.message || 'Failed to create subscription', 'error');
-            }
-        },
-
         // Delete store
         async deleteStore() {
             detailLog.info('Delete store requested:', this.storeCode);