feat(client): add Timestamp component, ESLint 10 + Prettier, and code quality fixes

- add Timestamp component with moment relative time and ISO tooltip
- add Timestamp stories (JustNow, MinutesAgo, HoursAgo, DaysAgo, MonthsAgo)
- add ESLint 10 with typescript-eslint, react-hooks, react-refresh, prettier
- add Prettier config with singleQuote, semi, trailingComma all, printWidth 100
- add lint, lint:fix, format, test:storybook scripts to package.json
- fix react-hooks/set-state-in-effect in all page components
- auto-fix 113 Prettier formatting issues across src and .storybook

client/src/pages/KeysPage.tsx

@@ -4,7 +4,9 @@ import { keys } from '../api';
 import { Table, type TableColumn } from '../ui';
 import styles from './Page.module.css';
 
-interface KeyRow { name: string }
+interface KeyRow {
+  name: string;
+}
 
 export function KeysPage() {
   const { t } = useTranslation();
@@ -17,8 +19,8 @@ export function KeysPage() {
   ];
 
   useEffect(() => {
-    setLoading(true);
-    keys.list()
+    keys
+      .list()
       .then((res) => setItems(res.keys.map((name) => ({ name }))))
       .catch((err: Error) => setError(err.message))
       .finally(() => setLoading(false));