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>

static/vendor/js/init-alpine.js

@@ -218,4 +218,53 @@ function languageSelector(currentLang, enabledLanguages) {
     };
 }
 
-window.languageSelector = languageSelector;
+window.languageSelector = languageSelector;
+
+/**
+ * Email Settings Warning Component
+ * Shows warning banner when vendor email settings are not configured
+ *
+ * Usage in template:
+ * <div x-data="emailSettingsWarning()" x-show="showWarning">...</div>
+ */
+function emailSettingsWarning() {
+    return {
+        showWarning: false,
+        loading: true,
+        vendorCode: null,
+
+        async init() {
+            // Get vendor code from URL
+            const path = window.location.pathname;
+            const segments = path.split('/').filter(Boolean);
+            if (segments[0] === 'vendor' && segments[1]) {
+                this.vendorCode = segments[1];
+            }
+
+            // Skip if we're on the settings page (to avoid showing banner on config page)
+            if (path.includes('/settings')) {
+                this.loading = false;
+                return;
+            }
+
+            // Check email settings status
+            await this.checkEmailStatus();
+        },
+
+        async checkEmailStatus() {
+            try {
+                const response = await apiClient.get('/vendor/email-settings/status');
+                // Show warning if not configured
+                this.showWarning = !response.is_configured;
+            } catch (error) {
+                // Don't show warning on error (might be 401, etc.)
+                console.debug('[EmailWarning] Failed to check email status:', error);
+                this.showWarning = false;
+            } finally {
+                this.loading = false;
+            }
+        }
+    };
+}
+
+window.emailSettingsWarning = emailSettingsWarning;