Add child relation deletion by parent query: Introduced a new SQL query to delete child relations where the character is either a father or mother. Updated relevant workers to execute this query before deleting child relations, ensuring proper cleanup of relationships during character deletion.

src/worker/sql.rs

@@ -544,6 +544,11 @@ WITH deleted AS (
 SELECT cf.user_id AS father_user_id, cm.user_id AS mother_user_id FROM deleted d JOIN falukant_data.character cf ON cf.id = d.father_character_id JOIN falukant_data.character cm ON cm.id = d.mother_character_id;
 "#;
 
+/// Entfernt alle child_relation-Zeilen, in denen der Charakter Vater oder Mutter ist (nötig vor Charakter-Löschung).
+pub const QUERY_DELETE_CHILD_RELATION_BY_PARENT: &str = r#"
+DELETE FROM falukant_data.child_relation WHERE father_character_id = $1 OR mother_character_id = $1;
+"#;
+
 pub const QUERY_DELETE_CHARACTER: &str = r#"
 DELETE FROM falukant_data.character WHERE id = $1;
 "#;