feat: loyalty feature provider, admin data fixes, storefront mobile menu

- Add LoyaltyFeatureProvider with 11 BINARY/MERCHANT features for billing
  feature gating, wired into loyalty module definition
- Fix subscription-tiers admin page showing 0 features by populating
  feature_codes from tier relationship in all admin tier endpoints
- Fix merchants admin page showing 0 stores and N/A owner by adding
  store_count and owner_email to MerchantResponse and eager-loading owner
- Add "no tiers" warning with link in subscription creation modal when
  platform has no configured tiers
- Add missing mobile menu panel to storefront base template so hamburger
  toggle actually shows navigation links

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

app/modules/tenancy/templates/tenancy/admin/merchant-detail.html

@@ -331,12 +331,20 @@
             <!-- Tier Selector -->
             <div class="mb-4">
                 <label class="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-1">Subscription Tier</label>
-                <select x-model="createForm.tier_code"
-                        class="w-full px-3 py-2 text-sm border border-gray-300 rounded-lg dark:border-gray-600 dark:bg-gray-700 dark:text-gray-300 focus:outline-none focus:ring-2 focus:ring-purple-500">
-                    <template x-for="tier in tiers" :key="tier.code">
-                        <option :value="tier.code" x-text="tier.name + ' — ' + formatTierPrice(tier)"></option>
-                    </template>
-                </select>
+                <template x-if="tiers.length > 0">
+                    <select x-model="createForm.tier_code"
+                            class="w-full px-3 py-2 text-sm border border-gray-300 rounded-lg dark:border-gray-600 dark:bg-gray-700 dark:text-gray-300 focus:outline-none focus:ring-2 focus:ring-purple-500">
+                        <template x-for="tier in tiers" :key="tier.code">
+                            <option :value="tier.code" x-text="tier.name + ' — ' + formatTierPrice(tier)"></option>
+                        </template>
+                    </select>
+                </template>
+                <template x-if="tiers.length === 0">
+                    <div class="p-3 text-sm text-amber-700 bg-amber-50 border border-amber-200 rounded-lg dark:text-amber-300 dark:bg-amber-900/20 dark:border-amber-800">
+                        No tiers configured for this platform.
+                        <a href="/admin/subscription-tiers" class="underline font-medium hover:text-amber-900 dark:hover:text-amber-100">Create a tier first</a>.
+                    </div>
+                </template>
             </div>
 
             <!-- Status -->
@@ -372,7 +380,7 @@
                     Cancel
                 </button>
                 <button @click="createSubscription()"
-                        :disabled="creatingSubscription"
+                        :disabled="creatingSubscription || tiers.length === 0"
                         class="px-4 py-2 text-sm font-medium text-white bg-purple-600 rounded-lg hover:bg-purple-700 disabled:opacity-50 disabled:cursor-not-allowed">
                     <span x-show="!creatingSubscription">Create</span>
                     <span x-show="creatingSubscription">Creating...</span>