fix: protection stacking + remove misleading def from combat card

getProtection(): replace threshold sum<4 with hasRealArmor check.
Old logic broke when two sub-4 items (e.g. shield 2 + light armor 3)
summed >=4 and lost the base+4 bonus — causing protection to decrease
when equipping them together.

actor-sheet.hbs: remove defenseTotal from top-right combat card.
This value excluded Mêlée skill, making it always wrong vs
the per-weapon defense shown in the combat tab.

templates/actor-sheet.hbs

@@ -111,10 +111,6 @@
             <label>{{localize "MNBL.initShort"}}</label>
             <span>{{combat.initTotal}}</span>
           </div>
-          <div class="stat-field">
-            <label>{{localize "MNBL.defShort"}}</label>
-            <span>{{combat.defenseTotal}}</span>
-          </div>
           <div class="stat-field">
             <label>{{localize "MNBL.protShort"}}</label>
             <span>{{protectionTotal}}</span>