feat(profile): implement user-initiated GDPR-compliant profile deletion

- Add DELETE /users/me endpoint with cascading data removal
- Implement frontend confirmation dialog and deletion flow
- Add audit logging for deletion requests
- Update localization files for new UI strings
- Add scheduled cleanup service for AI traces
- Document GDPR compliance in technical specification

BREAKING CHANGE: Users can now permanently delete their profiles and associated data

flutter/lib/l10n/app_en.arb

@@ -517,9 +517,10 @@
   "adminInlineCategory": "Category (inline)",
   "adminNoCategory": "No category",
   "adminRestoreAction": "Restore",
-  "required": "Required",
-  "logoutAction": "Log out",
-  "adminAiDescription": "Overview of AI features exposed by the backend.",
-  "adminPagePrefix": "Page: ",
+  "profileDeleteConfirmTitle": "Confirm deletion",
+  "profileDeleteConfirmMessage": "Are you sure you want to delete your profile? All your data will be permanently deleted.",
+  "profileDeleteAction": "Delete my profile",
+  "profileDeletedMessage": "Your profile has been deleted."
+}
   "profileDatabaseDescription": "The database tab covers your main areas for inventory and products."
 }