fix: re-register dayjs plugins in start to prevent cross-module conflicts

Move dayjs plugin initialization into `start()` and re-extend all loaded
`dayjs_plugin_*` plugins after module scripts are loaded. This makes
CalendarExt2 resilient when another module overwrites the global dayjs
instance, and removes the now-redundant `lib/dayjs-init.js`.

Author: KristjanESPERANTO

MMM-CalendarExt2.js

@@ -1,5 +1,5 @@
 /* eslint-disable no-eval */
-/* global Module Scene config */
+/* global Module Scene config dayjs */
 
 Module.register("MMM-CalendarExt2", {
   predefined: {
@@ -247,7 +247,6 @@ Module.register("MMM-CalendarExt2", {
     }
 
     scripts.push(
-      this.file("lib/dayjs-init.js"),
       "CALEXT2_Scene.js",
       "CALEXT2_View.js",
       "CALEXT2_Event.js",
@@ -281,6 +280,13 @@ Module.register("MMM-CalendarExt2", {
   },
 
   start () {
+    // Re-register all dayjs plugins after all module scripts are loaded to
+    // prevent other modules from overwriting the global dayjs object.
+    for (const key of Object.keys(window)) {
+      if (key.startsWith("dayjs_plugin_")) dayjs.extend(window[key]);
+    }
+    if (config.language) dayjs.locale(config.language.toLowerCase());
+
     this.rotateTimer = null;
     this.updateTimer = null;
     this.currentSceneUid = 0;