Fix: Replace missing effect.webp icon with existing capacite.webp

- effect.webp icon was missing, causing infinite 404 errors
- Replaced all references with capacite.webp which exists
- Fixed in base-actor-sheet.mjs, base-item-sheet.mjs, mournblade-cyd2-effects.js
- Fixed in partial-active-effects.hbs and partial-item-effects.hbs templates
- Updated test script to check for effect.webp references

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

templates/partial-item-effects.hbs

@@ -27,7 +27,7 @@
     {{#each item.effects as |effect|}}
     <li class="item flexrow" data-effect-id="{{effect.id}}" {{#if effect.disabled}}style="opacity: 0.6;"{{/if}}>
       {{!-- Icône de l'effet --}}
-      <img class="item-name-img" src="{{effect.icon}}" onerror="this.src='systems/fvtt-mournblade-cyd-2-0/assets/icons/effect.webp'" />
+      <img class="item-name-img" src="{{effect.icon}}" onerror="this.src='systems/fvtt-mournblade-cyd-2-0/assets/icons/capacite.webp'" />
       
       {{!-- Nom et description de l'effet --}}
       <div class="flexcol item-name-label">