refactor: remove modules system from core package

- Remove all module-related entry points from package.json exports
- Remove module source files from tsup build configuration
- Clean up external dependencies related to modules
- Update DEV.md to reflect modules removal from architecture
- Clarify package description to specify Next.js CMS

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@zen/core",
   "version": "1.3.13",
-  "description": "Un CMS construit sur l'essentiel, rien de plus, rien de moins.",
+  "description": "Un CMS Next.js construit sur l'essentiel, rien de plus, rien de moins.",
   "repository": {
     "type": "git",
     "url": "https://git.hyko.cx/zen/core.git"
@@ -115,36 +115,6 @@
     "./provider": {
       "import": "./dist/features/provider/index.js"
     },
-    "./core/modules": {
-      "import": "./dist/core/modules/index.js"
-    },
-    "./core/modules/client": {
-      "import": "./dist/core/modules/client.js"
-    },
-    "./modules": {
-      "import": "./dist/modules/index.js"
-    },
-    "./modules/define": {
-      "import": "./dist/core/modules/defineModule.js"
-    },
-    "./modules/pages": {
-      "import": "./dist/modules/pages.js"
-    },
-    "./modules/actions": {
-      "import": "./dist/modules/modules.actions.js"
-    },
-    "./modules/storage": {
-      "import": "./dist/modules/modules.storage.js"
-    },
-    "./modules/posts/crud": {
-      "import": "./dist/modules/posts/crud.js"
-    },
-    "./modules/metadata": {
-      "import": "./dist/modules/modules.metadata.js"
-    },
-    "./modules/page": {
-      "import": "./dist/modules/page.js"
-    },
     "./lib/metadata": {
       "import": "./dist/shared/lib/metadata/index.js"
     },