refactor(arch): eliminate all cross-module model imports in service layer

Enforce MOD-025/MOD-026 rules: zero top-level cross-module model imports
remain in any service file. All 66 files migrated using deferred import
patterns (method-body, _get_model() helpers, instance-cached self._Model)
and new cross-module service methods in tenancy. Documentation updated
with Pattern 6 (deferred imports), migration plan marked complete, and
violations status reflects 84→0 service-layer violations.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/cms/services/content_page_service.py

@@ -60,22 +60,9 @@ class ContentPageService:
         Returns:
             Platform ID or None if no platform association found
         """
-        from app.modules.tenancy.models import StorePlatform
+        from app.modules.tenancy.services.platform_service import platform_service
 
-        primary_sp = (
-            db.query(StorePlatform)
-            .filter(StorePlatform.store_id == store_id, StorePlatform.is_primary.is_(True))
-            .first()
-        )
-        if primary_sp:
-            return primary_sp.platform_id
-        # Fallback: any active store_platform
-        any_sp = (
-            db.query(StorePlatform)
-            .filter(StorePlatform.store_id == store_id, StorePlatform.is_active.is_(True))
-            .first()
-        )
-        return any_sp.platform_id if any_sp else None
+        return platform_service.get_primary_platform_id_for_store(db, store_id)
 
     @staticmethod
     def resolve_platform_id_or_raise(db: Session, store_id: int) -> int: