fix(web): translate the combat page's monster level badge to English

Closes a task-5 review finding: the fighter__level badge on the combat
page still read "Stufe {{ level }}"; the design doc gap that excluded
it has since been fixed. Changed to "Level {{ level }}" to match
encounter-card.component.html's pending equivalent (out of scope here).

apps/web/src/app/features/combat/combat-page/combat-page.component.html

@@ -26,7 +26,7 @@
           <div class="fighter__meter">
             <p class="fighter__name">
               {{ combat.monster.name }}
-              <span class="fighter__level">Stufe {{ combat.monster.level }}</span>
+              <span class="fighter__level">Level {{ combat.monster.level }}</span>
             </p>
             <div
               class="bar bar--monster"