feat: add email settings with database overrides for admin and vendor

Platform Email Settings (Admin):
- Add GET/PUT/DELETE /admin/settings/email/* endpoints
- Settings stored in admin_settings table override .env values
- Support all providers: SMTP, SendGrid, Mailgun, Amazon SES
- Edit mode UI with provider-specific configuration forms
- Reset to .env defaults functionality
- Test email to verify configuration

Vendor Email Settings:
- Add VendorEmailSettings model with one-to-one vendor relationship
- Migration: v0a1b2c3d4e5_add_vendor_email_settings.py
- Service: vendor_email_settings_service.py with tier validation
- API endpoints: /vendor/email-settings/* (CRUD, status, verify)
- Email tab in vendor settings page with full configuration
- Warning banner until email is configured (like billing warnings)
- Premium providers (SendGrid, Mailgun, SES) tier-gated to Business+

Email Service Updates:
- get_platform_email_config(db) checks DB first, then .env
- Configurable provider classes accept config dict
- EmailService uses database-aware providers
- Vendor emails use vendor's own SMTP (Wizamart doesn't pay)
- "Powered by Wizamart" footer for Essential/Professional tiers
- White-label (no footer) for Business/Enterprise tiers

Other:
- Add scripts/install.py for first-time platform setup
- Add make install target
- Update init-prod to include email template seeding

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/templates/shared/macros/feature_gate.html

@@ -335,3 +335,38 @@
     <span>Upgrade to <span x-text="$store.upgrade.nextTier?.name"></span></span>
 </a>
 {% endmacro %}
+
+
+{# =============================================================================
+   Email Settings Warning
+   Shows warning banner when vendor email settings are not configured.
+   This banner appears at the top of vendor pages until email is configured.
+
+   Usage:
+   {{ email_settings_warning() }}
+   ============================================================================= #}
+{% macro email_settings_warning() %}
+<div x-data="emailSettingsWarning()"
+     x-show="showWarning"
+     x-cloak
+     class="mb-4 p-4 bg-yellow-50 dark:bg-yellow-900/20 rounded-lg border border-yellow-200 dark:border-yellow-800">
+    <div class="flex items-center justify-between">
+        <div class="flex items-center">
+            <svg class="w-5 h-5 text-yellow-600 dark:text-yellow-400 mr-3 flex-shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2"
+                      d="M3 8l7.89 5.26a2 2 0 002.22 0L21 8M5 19h14a2 2 0 002-2V7a2 2 0 00-2-2H5a2 2 0 00-2 2v10a2 2 0 002 2z"/>
+            </svg>
+            <div>
+                <p class="font-medium text-yellow-800 dark:text-yellow-300">Email not configured</p>
+                <p class="text-sm text-yellow-700 dark:text-yellow-400">
+                    Configure your email settings to send order confirmations and customer notifications.
+                </p>
+            </div>
+        </div>
+        <a :href="`/vendor/${vendorCode}/settings?tab=email`"
+           class="ml-4 px-4 py-2 text-sm font-medium text-yellow-800 bg-yellow-200 rounded-lg hover:bg-yellow-300 dark:bg-yellow-800 dark:text-yellow-200 dark:hover:bg-yellow-700 whitespace-nowrap">
+            Configure Email
+        </a>
+    </div>
+</div>
+{% endmacro %}