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/installation/Step3DatabaseConfig.vue

@@ -15,7 +15,7 @@
 </template>
 
 <script>
-import { ref, computed, onMounted } from 'vue'
+import { ref, computed, onMounted, watch } from 'vue'
 import Mysql from './database/MysqlDatabase.vue'
 import Pgsql from './database/PgsqlDatabase.vue'
 import Sqlite from './database/SqliteDatabase.vue'
@@ -41,10 +41,11 @@ export default {
     const notificationStore = useNotificationStore()
     const installationStore = useInstallationStore()
 
-    const databaseData = computed(() => {
-      installationStore.currentDataBaseData.app_locale = global.locale.value
-      return installationStore.currentDataBaseData
-    })
+    const databaseData = computed(() => installationStore.currentDataBaseData)
+
+    watch(() => global.locale.value, (newLocale) => {
+      installationStore.currentDataBaseData.app_locale = newLocale
+    }, { immediate: true })
 
     async function getDatabaseConfig(connection) {
       let params = {}