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/ui/Button/Button.tsx

@@ -18,7 +18,9 @@ export function Button({
 }: ButtonProps) {
   return (
     <button
-      className={[styles.button, styles[variant], styles[size], className].filter(Boolean).join(' ')}
+      className={[styles.button, styles[variant], styles[size], className]
+        .filter(Boolean)
+        .join(' ')}
       disabled={disabled || loading}
       {...props}
     >