[Server] Expose the audit log on the database interface

addAuditRecord existed only on Servatrice_DatabaseInterface, so 37 moderator and admin commands reached through the concrete class just to append a log row. Declare it on Server_DatabaseInterface with an empty default, mark the Servatrice implementation as an override, and switch the handler's call sites to the injected interface. No SQL moves; the argument hashes are unchanged.

servatrice/src/servatrice_database_interface.h

@@ -302,7 +302,7 @@ public:
                         const QString &clientid,
                         const QString &action,
                         const QString &details,
-                        const bool &results);
+                        bool results) override;
 };
 
 #endif