Upgrade eslint tooling to v10 and fix linting bugs (#601)

- Upgrade eslint 9→10, eslint-config-prettier 9→10, eslint-plugin-vue 9→10
- Upgrade @types/node 20→24
- Migrate from legacy .eslintrc.mjs to flat config eslint.config.mjs
- Remove --ext flag from npm test script (dropped in eslint 10)
- Fix vue/no-ref-as-operand: add missing .value to ref assignments (5 files)
- Fix vue/return-in-computed-property: add default returns (2 files)
- Fix vue/no-side-effects-in-computed-properties: move mutation to watcher
- Fix vue/no-dupe-keys: remove ref shadowing prop in DomPDFDriver
- Fix vue/no-deprecated-slot-attribute: migrate to v-slot syntax (3 files)
- Fix vue/require-valid-default-prop: use factory function for array default
- Fix vue/no-unused-vars: remove unused slot destructure
- Disable vue/no-mutating-props (false positive for Pinia store props)

resources/scripts/admin/views/modules/View.vue

@@ -908,19 +908,19 @@ function getErrorMessage(message) {
 
   switch (message) {
     case 'module_not_found':
-      msg = t('modules.module_not_found')
+      msg.value = t('modules.module_not_found')
       break
 
     case 'module_not_purchased':
-      msg = t('modules.module_not_purchased')
+      msg.value = t('modules.module_not_purchased')
       break
 
     case 'version_not_supported':
-      msg = t('modules.version_not_supported')
+      msg.value = t('modules.version_not_supported')
       break
 
     default:
-      msg = message
+      msg.value = message
       break
   }