feat: retreat stops attack + show when ennemy retreats (openfrontio#209)

Author: ilan-schemoul

src/client/graphics/layers/EventsDisplay.ts

@@ -419,6 +419,7 @@ export class EventsDisplay extends LitElement implements Layer {
                         ) as PlayerView
                       )?.name()}
                     </button>
+                    ${attack.retreating ? "(retreating...)" : ""}
                   `,
                 )}
               </td>

src/core/execution/AttackExecution.ts

@@ -185,6 +185,10 @@ export class AttackExecution implements Execution {
       return;
     }
 
+    if (this.attack.retreating()) {
+      return;
+    }
+
     if (!this.attack.isActive()) {
       this.active = false;
       return;