feat: implement vendor landing pages with multi-template support and fix shop routing

Major improvements to shop URL routing and vendor landing page system:

## Landing Page System
- Add template field to ContentPage model for flexible landing page designs
- Create 4 landing page templates: default, minimal, modern, and full
- Implement smart root handler to serve landing pages or redirect to shop
- Add create_landing_page.py script for easy landing page management
- Support both domain/subdomain and path-based vendor access
- Add comprehensive landing page documentation

## Route Fixes
- Fix duplicate /shop prefix in shop_pages.py routes
- Correct product detail page routing (was /shop/shop/products/{id})
- Update all shop routes to work with router prefix mounting
- Remove unused public vendor endpoints (/api/v1/public/vendors)

## Template Link Corrections
- Fix all shop template links to include /shop/ prefix
- Update breadcrumb 'Home' links to point to vendor root (landing page)
- Update header navigation 'Home' link to point to vendor root
- Correct CMS page links in footer navigation
- Fix account, cart, and error page navigation links

## Navigation Architecture
- Establish two-tier navigation: landing page (/) and shop (/shop/)
- Document complete navigation flow and URL hierarchy
- Support for vendors with or without landing pages (auto-redirect fallback)
- Consistent breadcrumb and header navigation behavior

## Documentation
- Add vendor-landing-pages.md feature documentation
- Add navigation-flow.md with complete URL hierarchy
- Update shop architecture docs with error handling section
- Add orphaned docs to mkdocs.yml navigation
- Document multi-access routing patterns

## Database
- Migration f68d8da5315a: add template field to content_pages table
- Support template values: default, minimal, modern, full

This establishes a complete landing page system allowing vendors to have
custom marketing homepages separate from their e-commerce shop, with
flexible template options and proper navigation hierarchy.

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

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

main.py

@@ -230,6 +230,48 @@ app.include_router(
     include_in_schema=False
 )
 
+# Add handler for /vendors/{vendor_code}/ root path
+@app.get("/vendors/{vendor_code}/", response_class=HTMLResponse, include_in_schema=False)
+async def vendor_root_path(vendor_code: str, request: Request, db: Session = Depends(get_db)):
+    """Handle vendor root path (e.g., /vendors/wizamart/)"""
+    # Vendor should already be in request.state from middleware
+    vendor = getattr(request.state, 'vendor', None)
+
+    if not vendor:
+        raise HTTPException(status_code=404, detail=f"Vendor '{vendor_code}' not found")
+
+    from app.services.content_page_service import content_page_service
+    from app.routes.shop_pages import get_shop_context
+
+    # Try to find landing page
+    landing_page = content_page_service.get_page_for_vendor(
+        db,
+        slug="landing",
+        vendor_id=vendor.id,
+        include_unpublished=False
+    )
+
+    if not landing_page:
+        landing_page = content_page_service.get_page_for_vendor(
+            db,
+            slug="home",
+            vendor_id=vendor.id,
+            include_unpublished=False
+        )
+
+    if landing_page:
+        # Render landing page with selected template
+        template_name = landing_page.template or "default"
+        template_path = f"vendor/landing-{template_name}.html"
+
+        return templates.TemplateResponse(
+            template_path,
+            get_shop_context(request, db=db, page=landing_page)
+        )
+    else:
+        # No landing page - redirect to shop
+        return RedirectResponse(url=f"/vendors/{vendor_code}/shop/", status_code=302)
+
 logger.info("=" * 80)
 
 # Log all registered routes
@@ -247,10 +289,61 @@ logger.info("=" * 80)
 # ============================================================================
 
 # Public Routes (no authentication required)
-@app.get("/", include_in_schema=False)
-async def root():
-    """Redirect root to documentation"""
-    return RedirectResponse(url="/documentation")
+@app.get("/", response_class=HTMLResponse, include_in_schema=False)
+async def root(request: Request, db: Session = Depends(get_db)):
+    """
+    Smart root handler:
+    - If vendor detected (domain/subdomain): Show vendor landing page or redirect to shop
+    - If no vendor (platform root): Redirect to documentation
+    """
+    vendor = getattr(request.state, 'vendor', None)
+
+    if vendor:
+        # Vendor context detected - serve landing page
+        from app.services.content_page_service import content_page_service
+
+        # Try to find landing page (slug='landing' or 'home')
+        landing_page = content_page_service.get_page_for_vendor(
+            db,
+            slug="landing",
+            vendor_id=vendor.id,
+            include_unpublished=False
+        )
+
+        if not landing_page:
+            # Try 'home' slug as fallback
+            landing_page = content_page_service.get_page_for_vendor(
+                db,
+                slug="home",
+                vendor_id=vendor.id,
+                include_unpublished=False
+            )
+
+        if landing_page:
+            # Render landing page with selected template
+            from app.routes.shop_pages import get_shop_context
+
+            template_name = landing_page.template or "default"
+            template_path = f"vendor/landing-{template_name}.html"
+
+            return templates.TemplateResponse(
+                template_path,
+                get_shop_context(request, db=db, page=landing_page)
+            )
+        else:
+            # No landing page - redirect to shop
+            vendor_context = getattr(request.state, 'vendor_context', None)
+            access_method = vendor_context.get('detection_method', 'unknown') if vendor_context else 'unknown'
+
+            if access_method == "path":
+                full_prefix = vendor_context.get('full_prefix', '/vendor/') if vendor_context else '/vendor/'
+                return RedirectResponse(url=f"{full_prefix}{vendor.subdomain}/shop/", status_code=302)
+            else:
+                # Domain/subdomain
+                return RedirectResponse(url="/shop/", status_code=302)
+    else:
+        # No vendor - platform root
+        return RedirectResponse(url="/documentation")
 
 
 @app.get("/health")