Fix protection and other maintained status effects

Protection and other system status effects still had a duration when
being maintained.

Fixes #44

src/module/powers/basePowers.js

@@ -134,13 +134,12 @@ export class PowerEffect {
   static async getStatus(label, name, favorite = true) {
     const effect = foundry.utils.deepClone(CONFIG.statusEffects.find((se) => se.label === label || se.name === label));
     effect.name = 'name' in effect ? effect.name : effect.label;
+    effect.duration = {};
     if (!('flags' in effect)) {
       effect.flags = {};
     }
+    effect.flags.swade = {};
     if (favorite) {
-      if (!('swade' in effect.flags)) {
-        effect.flags.swade = {};
-      }
       effect.flags.swade.favorite = true;
     }
     effect.statuses ??= [];