fix(mobile): align background, API config, and search bar with PWA

- Add background image matching PWA (bg.png with opacity + overlay)
- Fix production API URL to farmacias.hacecalor.net
- Replace raw fetch calls in alerts.tsx with configured api service
- Constrain SearchBar max-width to 420px to prevent horizontal clipping

apps/frontend-mobile/app/(tabs)/alerts.tsx

@@ -3,6 +3,7 @@ import { View, Text, StyleSheet, FlatList, TouchableOpacity, Alert, useWindowDim
 import { Ionicons } from '@expo/vector-icons';
 import { colors, spacing, borderRadius, shadows } from '../../constants/theme';
 import { LoadingSpinner } from '../../components/LoadingSpinner';
+import api from '../../services/api';
 
 const TABLET_MIN_WIDTH = 768;
 
@@ -33,9 +34,8 @@ export default function AlertsScreen() {
     setIsLoading(true);
     setError(null);
     try {
-      const res = await fetch('/api/notifications/mine', { credentials: 'include' });
-      if (!res.ok) throw new Error(`HTTP ${res.status}`);
-      const data = await res.json();
+      const res = await api.get('/notifications/mine');
+      const data = res.data;
       const merged = [
         ...(data.pharmacy || []),
         ...(data.global || []),
@@ -63,13 +63,9 @@ export default function AlertsScreen() {
           onPress: async () => {
             setDeletingId(key);
             try {
-              const res = await fetch('/api/notifications/mine', {
-                method: 'DELETE',
-                headers: { 'Content-Type': 'application/json' },
-                credentials: 'include',
-                body: JSON.stringify({ scope: item.scope, id: item.id }),
+              await api.delete('/notifications/mine', {
+                data: { scope: item.scope, id: item.id },
               });
-              if (!res.ok && res.status !== 204) throw new Error(`HTTP ${res.status}`);
               setItems(prev => prev.filter(i => !(i.scope === item.scope && i.id === item.id)));
             } catch (err: any) {
               Alert.alert('Error', err.message || 'No se pudo eliminar');

apps/frontend-mobile/app/(tabs)/index.tsx

@@ -100,7 +100,10 @@ const styles = StyleSheet.create({
   searchContainer: {
     flexDirection: 'row',
     alignItems: 'center',
-    paddingRight: spacing.lg,
+    paddingHorizontal: spacing.lg,
+    maxWidth: 480,
+    alignSelf: 'center',
+    width: '100%',
   },
   searchContainerTablet: {
     maxWidth: 700,