feat(core)!: introduce runtime extension registry and flat module conventions

BREAKING CHANGE: sup config now derives entries from package.json#exports and a server/client glob instead of manual lists; module structure follows flat + barrel convention with .server.js/.client.js runtime suffixes

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "@zen/core",
-  "version": "1.3.47",
+  "version": "1.4.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@zen/core",
-      "version": "1.3.47",
+      "version": "1.4.1",
       "license": "GPL-3.0-only",
       "dependencies": {
         "@headlessui/react": "^2.0.0",