feat: Complete high-priority i18n localization with date/time support

This commit implements comprehensive localization for high-priority components:

## Tracking Pages (4 files)
- Localized feeding, sleep, diaper, and medicine tracking pages
- Replaced hardcoded strings with translation keys from tracking namespace
- Added useTranslation hook integration
- All form labels, buttons, and messages now support multiple languages

## Child Dialog Components (2 files)
- Localized ChildDialog (add/edit child form)
- Localized DeleteConfirmDialog
- Added new translation keys to children.json for dialog content
- Includes validation messages and action buttons

## Date/Time Localization (14 files + new hook)
- Created useLocalizedDate hook wrapping date-fns with locale support
- Supports 5 languages: English, Spanish, French, Portuguese, Chinese
- Updated all date formatting across:
  * Tracking pages (feeding, sleep, diaper, medicine)
  * Activity pages (activities, history, track activity)
  * Settings components (sessions, biometric, device trust)
  * Analytics components (insights, growth, sleep chart, feeding graph)
- Date displays automatically adapt to user's language (e.g., "2 hours ago" → "hace 2 horas")

## Translation Updates
- Enhanced children.json with dialog section containing:
  * Form field labels (name, birthDate, gender, photoUrl)
  * Action buttons (add, update, delete, cancel, saving, deleting)
  * Delete confirmation messages
  * Validation error messages

Files changed: 17 files (+164, -113)
Languages supported: en, es, fr, pt-BR, zh-CN

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

maternal-web/hooks/useLocalizedDate.ts

@@ -0,0 +1,92 @@
+import { useTranslation } from './useTranslation';
+import {
+  format as dateFnsFormat,
+  formatDistanceToNow as dateFnsFormatDistanceToNow,
+  formatDistance as dateFnsFormatDistance,
+  formatRelative as dateFnsFormatRelative,
+} from 'date-fns';
+import { enUS, es, fr, ptBR, zhCN } from 'date-fns/locale';
+
+/**
+ * Map of i18next language codes to date-fns locales
+ */
+const localeMap: Record<string, Locale> = {
+  'en': enUS,
+  'en-US': enUS,
+  'es': es,
+  'es-ES': es,
+  'fr': fr,
+  'fr-FR': fr,
+  'pt': ptBR,
+  'pt-BR': ptBR,
+  'zh': zhCN,
+  'zh-CN': zhCN,
+};
+
+/**
+ * Custom hook for localized date formatting using date-fns
+ * Automatically applies the correct locale based on the current i18n language
+ */
+export function useLocalizedDate() {
+  const { language } = useTranslation();
+
+  // Get the locale for the current language, fallback to enUS
+  const locale = localeMap[language] || enUS;
+
+  /**
+   * Format a date using date-fns with the current locale
+   * @param date - The date to format
+   * @param formatStr - The format string (e.g., 'PPP', 'MM/dd/yyyy')
+   */
+  const format = (date: Date | number | string, formatStr: string): string => {
+    const dateObj = typeof date === 'string' ? new Date(date) : date;
+    return dateFnsFormat(dateObj, formatStr, { locale });
+  };
+
+  /**
+   * Format a date as a distance to now (e.g., "2 hours ago")
+   * @param date - The date to format
+   * @param options - Optional options for formatDistanceToNow
+   */
+  const formatDistanceToNow = (
+    date: Date | number | string,
+    options?: { addSuffix?: boolean; includeSeconds?: boolean }
+  ): string => {
+    const dateObj = typeof date === 'string' ? new Date(date) : date;
+    return dateFnsFormatDistanceToNow(dateObj, { ...options, locale });
+  };
+
+  /**
+   * Format the distance between two dates
+   * @param date - The later date
+   * @param baseDate - The earlier date
+   * @param options - Optional options for formatDistance
+   */
+  const formatDistance = (
+    date: Date | number,
+    baseDate: Date | number,
+    options?: { addSuffix?: boolean; includeSeconds?: boolean }
+  ): string => {
+    return dateFnsFormatDistance(date, baseDate, { ...options, locale });
+  };
+
+  /**
+   * Format a date relative to now (e.g., "today at 5:00 PM")
+   * @param date - The date to format
+   * @param baseDate - Optional base date (defaults to now)
+   */
+  const formatRelative = (
+    date: Date | number,
+    baseDate?: Date | number
+  ): string => {
+    return dateFnsFormatRelative(date, baseDate || new Date(), { locale });
+  };
+
+  return {
+    format,
+    formatDistanceToNow,
+    formatDistance,
+    formatRelative,
+    locale,
+  };
+}