Add permission checks to p.prefix command

src/database/migrations/0001_init.cql

@@ -144,7 +144,7 @@ CREATE TABLE IF NOT EXISTS payphone.user_incidents (
     expires_at TIMESTAMP,
     duration ASCII,
 
-    PRIMARY KEY (user_id)
+    PRIMARY KEY (user_id, incident_id)
 );
 
 CREATE TABLE IF NOT EXISTS payphone.server_incidents (