feat: comprehensive vendor settings overhaul with Company inheritance

- Add structured API response with business_info, localization, letzshop,
  invoice_settings, theme_settings, domains, and stripe_info sections
- Add PUT /vendor/settings/business-info with reset_to_company capability
- Add PUT /vendor/settings/letzshop with validation for tax rates, delivery
- Add 9 settings sections: General, Business Info, Localization, Marketplace,
  Invoices, Branding, Domains, API & Payments, Notifications
- Business Info shows "Inherited" badges and Reset buttons for company fields
- Marketplace section includes Letzshop CSV URLs and feed options
- Read-only sections for Invoices, Branding, Domains, API with contact support
- Add globe-alt icon for Domains section
- Document email templates architecture for future implementation

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

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

docs/implementation/email-templates-architecture.md

@@ -0,0 +1,107 @@
+# Email Templates Architecture (Future)
+
+## Overview
+
+Email templates follow a similar pattern to the CMS content pages system, with platform defaults that vendors can override.
+
+## Architecture
+
+### Template Hierarchy
+
+1. **Platform Default Templates** - Admin-managed base templates
+   - Order confirmation
+   - Shipping notification
+   - Password reset
+   - Welcome email
+   - Invoice email
+   - etc.
+
+2. **Vendor Overrides** - Optional customization
+   - Vendors can override platform templates
+   - Cannot create new template types (unlike CMS pages)
+   - Must maintain required placeholders
+
+### Multi-language Support
+
+- Each template exists in all supported languages (FR, EN, DE, LB)
+- Vendor overrides are per-language
+- Falls back to platform default if no vendor override
+
+### Key Differences from CMS Pages
+
+| Feature | CMS Pages | Email Templates |
+|---------|-----------|-----------------|
+| Create new | Vendors can create | Vendors cannot create |
+| Template types | Unlimited | Fixed set by platform |
+| Tier limits | Number of pages per tier | No limits (all templates available) |
+| Override | Full content | Full content |
+
+## Database Design (Proposed)
+
+```sql
+-- Platform templates (admin-managed)
+CREATE TABLE email_templates (
+    id SERIAL PRIMARY KEY,
+    template_key VARCHAR(100) NOT NULL,  -- e.g., 'order_confirmation'
+    language VARCHAR(5) NOT NULL,         -- e.g., 'fr', 'en', 'de'
+    subject TEXT NOT NULL,
+    html_body TEXT NOT NULL,
+    text_body TEXT,
+    placeholders JSONB,                   -- Required placeholders
+    is_active BOOLEAN DEFAULT TRUE,
+    created_at TIMESTAMP,
+    updated_at TIMESTAMP,
+    UNIQUE(template_key, language)
+);
+
+-- Vendor overrides
+CREATE TABLE vendor_email_templates (
+    id SERIAL PRIMARY KEY,
+    vendor_id INTEGER REFERENCES vendors(id),
+    template_key VARCHAR(100) NOT NULL,
+    language VARCHAR(5) NOT NULL,
+    subject TEXT NOT NULL,
+    html_body TEXT NOT NULL,
+    text_body TEXT,
+    is_active BOOLEAN DEFAULT TRUE,
+    created_at TIMESTAMP,
+    updated_at TIMESTAMP,
+    UNIQUE(vendor_id, template_key, language)
+);
+```
+
+## Rendering Flow
+
+1. Email service receives request (e.g., send order confirmation)
+2. Check for vendor override by `(vendor_id, template_key, language)`
+3. If no override, use platform default by `(template_key, language)`
+4. Render template with context variables
+5. Send via email service
+
+## API Endpoints (Proposed)
+
+### Admin
+- `GET /admin/email-templates` - List all platform templates
+- `GET /admin/email-templates/{key}` - Get template by key
+- `PUT /admin/email-templates/{key}` - Update platform template
+- `POST /admin/email-templates/{key}/preview` - Preview template
+
+### Vendor
+- `GET /vendor/email-templates` - List available templates with override status
+- `GET /vendor/email-templates/{key}` - Get template (override or platform)
+- `PUT /vendor/email-templates/{key}` - Create/update override
+- `DELETE /vendor/email-templates/{key}` - Remove override (revert to platform)
+- `POST /vendor/email-templates/{key}/preview` - Preview with vendor context
+
+## UI Considerations
+
+- Admin: Template editor with WYSIWYG or code view
+- Vendor: Simple override interface showing platform default as reference
+- Placeholder validation on save
+- Preview with sample data
+
+## Notes
+
+- Email templates feature is NOT part of the current settings page
+- Contact support messaging in settings directs vendors to admin
+- Full implementation to follow CMS pages pattern