chore: rename package from @hykocx/zen to @zen/core

Update all references across source files, documentation, and
configuration to reflect the new package scope and name. This includes
updating `.npmrc` registry config, install instructions, module
examples, and all import path comments throughout the codebase.

package-lock.json

@@ -1,12 +1,12 @@
 {
-  "name": "@hykocx/zen",
-  "version": "1.3.2",
+  "name": "@zen/core",
+  "version": "1.3.3",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
-      "name": "@hykocx/zen",
-      "version": "1.3.2",
+      "name": "@zen/core",
+      "version": "1.3.3",
       "license": "GPL-3.0-only",
       "dependencies": {
         "@headlessui/react": "^2.0.0",