feat: add platform marketing homepage with signup flow

Implement complete marketing homepage for Wizamart targeting Letzshop
vendors in Luxembourg. Includes:

- Marketing homepage with hero, pricing tiers, and add-ons
- 4-step signup wizard with Stripe card collection (30-day trial)
- Letzshop vendor lookup for shop claiming
- Platform API endpoints for pricing, vendors, and signup
- Stripe SetupIntent integration for trial with card upfront
- Database fields for Letzshop vendor identity tracking

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

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

main.py

@@ -37,7 +37,7 @@ from app.exceptions import ServiceUnavailableException
 from app.exceptions.handler import setup_exception_handlers
 
 # Import page routers
-from app.routes import admin_pages, shop_pages, vendor_pages
+from app.routes import admin_pages, platform_pages, shop_pages, vendor_pages
 from middleware.context import ContextMiddleware
 from middleware.language import LanguageMiddleware
 from middleware.logging import LoggingMiddleware
@@ -244,6 +244,12 @@ logger.info("=" * 80)
 logger.info("ROUTE REGISTRATION")
 logger.info("=" * 80)
 
+# Platform marketing pages (homepage, pricing, signup)
+logger.info("Registering platform page routes: /*, /pricing, /find-shop, /signup")
+app.include_router(
+    platform_pages.router, prefix="", tags=["platform-pages"], include_in_schema=False
+)
+
 # Admin pages
 logger.info("Registering admin page routes: /admin/*")
 app.include_router(