Refactor database error handling across repositories to use IntoDbResult for improved error management

- Updated PgNotificationRepository to utilize IntoDbResult for error handling in various methods.
- Refactored PgRemoteActorRepository to replace manual error mapping with IntoDbResult.
- Modified PgRemoteActorConnectionRepository to implement IntoDbResult for error handling.
- Adjusted PgTagRepository to use IntoDbResult for consistent error management.
- Introduced test_helpers module for seeding users and thoughts in tests.
- Enhanced PgThoughtRepository to leverage IntoDbResult for error handling.
- Updated PgTopFriendRepository to utilize IntoDbResult for error management.
- Refactored PgUserRepository to implement IntoDbResult for error handling.
- Added constants for pagination defaults in requests.
- Introduced MAX_TOP_FRIENDS constant for top friends validation.
- Refactored JWT expiration time to use a constant.
- Improved rate limiter configuration with constants for better readability.
- Added utility methods for FollowState and Visibility enums for string conversions.
- Introduced maximum length constants for Username, Email, and Content value objects.
- Cleaned up test modules by removing redundant code and utilizing a shared testing state.

crates/domain/src/models/thought.rs

@@ -34,6 +34,15 @@ impl Visibility {
             Visibility::Direct => "direct",
         }
     }
+
+    pub fn from_db_str(s: &str) -> Self {
+        match s {
+            "followers" => Self::Followers,
+            "unlisted" => Self::Unlisted,
+            "direct" => Self::Direct,
+            _ => Self::Public,
+        }
+    }
 }
 
 impl Thought {