Implement currency, shops, and enhanced NPC interaction system

src/tick.rs

@@ -51,7 +51,7 @@ pub async fn run_tick_engine(state: SharedState) {
                     continue;
                 }
                 let att = st.npc_attitude_toward(npc_id, &conn.player.name);
-                if att.will_attack() {
+                if att.is_hostile() {
                     new_combats.push((*pid, npc_id.clone()));
                     break;
                 }