refactor: rename platform_domain → main_domain to avoid confusion with platform.domain

The setting `settings.platform_domain` (the global/main domain like "wizard.lu")
was easily confused with `platform.domain` (per-platform domain like "rewardflow.lu").
Renamed to `settings.main_domain` / `MAIN_DOMAIN` env var across the entire codebase.

Also updated docs to reflect the refactored store detection logic with
`is_platform_domain` / `is_subdomain_of_platform` guards.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/billing/routes/api/store_addons.py

@@ -144,7 +144,7 @@ def purchase_addon(
     store = billing_service.get_store(db, store_id)
 
     # Build URLs
-    base_url = f"https://{settings.platform_domain}"
+    base_url = f"https://{settings.main_domain}"
     success_url = f"{base_url}/store/{store.store_code}/billing?addon_success=true"
     cancel_url = f"{base_url}/store/{store.store_code}/billing?addon_cancelled=true"
 

app/modules/billing/routes/api/store_checkout.py

@@ -59,7 +59,7 @@ def create_checkout_session(
 
     store_code = subscription_service.get_store_code(db, store_id)
 
-    base_url = f"https://{settings.platform_domain}"
+    base_url = f"https://{settings.main_domain}"
     success_url = f"{base_url}/store/{store_code}/billing?success=true"
     cancel_url = f"{base_url}/store/{store_code}/billing?cancelled=true"
 
@@ -87,7 +87,7 @@ def create_portal_session(
     merchant_id, platform_id = subscription_service.resolve_store_to_merchant(db, store_id, current_user.token_platform_id)
 
     store_code = subscription_service.get_store_code(db, store_id)
-    return_url = f"https://{settings.platform_domain}/store/{store_code}/billing"
+    return_url = f"https://{settings.main_domain}/store/{store_code}/billing"
 
     result = billing_service.create_portal_session(db, merchant_id, platform_id, return_url)
 

app/modules/billing/services/signup_service.py

@@ -617,7 +617,7 @@ class SignupService:
 
             # Build login URL
             login_url = (
-                f"https://{settings.platform_domain}"
+                f"https://{settings.main_domain}"
                 f"/store/{store.store_code}/dashboard"
             )
 

app/modules/core/utils/page_context.py

@@ -205,7 +205,7 @@ def _build_base_context(
         "request": request,
         "platform": platform,
         "platform_name": settings.project_name,
-        "platform_domain": settings.platform_domain,
+        "main_domain": settings.main_domain,
     }
 
     # Add i18n globals

app/modules/tenancy/models/store.py

@@ -335,19 +335,19 @@ class Store(Base, TimestampMixin):
         Domain Resolution Priority:
         1. Store-specific custom domain (StoreDomain) -> highest priority
         2. Merchant domain (MerchantDomain) -> inherited default
-        3. Store subdomain ({store.subdomain}.{platform_domain}) -> fallback
+        3. Store subdomain ({store.subdomain}.{main_domain}) -> fallback
         """
         if self.primary_domain:
             return self.primary_domain
         if self.merchant and self.merchant.primary_domain:
             return self.merchant.primary_domain
-        return f"{self.subdomain}.{settings.platform_domain}"
+        return f"{self.subdomain}.{settings.main_domain}"
 
     @property
     def all_domains(self):
         """Get all active domains (subdomain + custom domains)."""
         domains = [
-            f"{self.subdomain}.{settings.platform_domain}"
+            f"{self.subdomain}.{settings.main_domain}"
         ]  # Start with the main subdomain
         for domain in self.domains:
             if domain.is_active: