refactor: imports and reorganize domain structure

- Updated import statements across multiple modules to use relative imports for better encapsulation.
- Consolidated and organized the `__init__.py` files in various domain packages to expose necessary classes and functions.
- Improved code readability and maintainability by grouping related imports and removing unused ones.
- Ensured consistent import patterns across the domain, enhancing the overall structure of the codebase.

domain/email/__init__.py

@@ -0,0 +1,20 @@
+from .service import EmailService, EmailTemplateRenderer
+from .types import (
+    EmailConfig,
+    EmailSecurity,
+    EmailSendPayload,
+    EmailTemplatePreviewPayload,
+    EmailTemplateUpdate,
+    EmailTestRequest,
+)
+
+__all__ = [
+    "EmailService",
+    "EmailTemplateRenderer",
+    "EmailConfig",
+    "EmailSecurity",
+    "EmailSendPayload",
+    "EmailTemplatePreviewPayload",
+    "EmailTemplateUpdate",
+    "EmailTestRequest",
+]