fix: register _dice-breakdown.hbs partial, await ready hook promises

Mulligan reroll reaction message creation was failing silently because
the chat/dice-breakdown Handlebars partial was never registered via
loadTemplates. This caused an unhandled promise rejection that aborted
the entire reroll handler chain — no mulligan message, no combat result.

lethal-fantasy.mjs

@@ -108,11 +108,16 @@ function preLocalizeConfig() {
   }
 }
 
-Hooks.once("ready", function () {
+Hooks.once("ready", async function () {
   console.info("LETHAL FANTASY | Ready")
 
   // Initialiser la table des résultats D30
-  documents.D30Roll.initialize()
+  await documents.D30Roll.initialize()
+
+  // Register Handlebars partials used by chat templates
+  await foundry.applications.handlebars.loadTemplates([
+    "systems/fvtt-lethal-fantasy/templates/chat/_dice-breakdown.hbs"
+  ])
 
   // Saignement piloté par le combat tracker
   _registerBleedingHooks()