feat: implement home screen with medicine search

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

@@ -1,10 +1,78 @@
-import { View, Text, StyleSheet } from 'react-native';
+import React, { useState, useEffect } from 'react';
+import { View, FlatList, StyleSheet, Text } from 'react-native';
+import { SearchBar } from '../../components/SearchBar';
+import { MedicineCard } from '../../components/MedicineCard';
+import { LoadingSpinner } from '../../components/LoadingSpinner';
+import { useDebounce } from '../../hooks/useDebounce';
+import { searchMedicines } from '../../services/medicines';
+import { colors, spacing } from '../../constants/theme';
+import { Medicine } from '../../types';
+import { config } from '../../constants/config';
 
 export default function HomeScreen() {
+  const [query, setQuery] = useState('');
+  const [results, setResults] = useState<Medicine[]>([]);
+  const [isLoading, setIsLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  
+  const debouncedQuery = useDebounce(query, config.SEARCH_DEBOUNCE_MS);
+
+  useEffect(() => {
+    if (debouncedQuery.length < 2) {
+      setResults([]);
+      return;
+    }
+
+    const fetchResults = async () => {
+      setIsLoading(true);
+      setError(null);
+      try {
+        const data = await searchMedicines(debouncedQuery);
+        setResults(data);
+      } catch (err) {
+        setError('Error al buscar medicamentos');
+        console.error(err);
+      } finally {
+        setIsLoading(false);
+      }
+    };
+
+    fetchResults();
+  }, [debouncedQuery]);
+
+  const handleSearch = (searchQuery: string) => {
+    setQuery(searchQuery);
+  };
+
   return (
     <View style={styles.container}>
-      <Text style={styles.title}>FarmaFinder</Text>
-      <Text style={styles.subtitle}>Busca medicamentos</Text>
+      <SearchBar
+        onSearch={handleSearch}
+        value={query}
+        onChangeText={setQuery}
+      />
+      
+      {isLoading && <LoadingSpinner message="Buscando medicamentos..." />}
+      
+      {error && (
+        <View style={styles.errorContainer}>
+          <Text style={styles.errorText}>{error}</Text>
+        </View>
+      )}
+      
+      {!isLoading && !error && results.length === 0 && query.length >= 2 && (
+        <View style={styles.emptyContainer}>
+          <Text style={styles.emptyText}>No se encontraron medicamentos</Text>
+        </View>
+      )}
+      
+      <FlatList
+        data={results}
+        keyExtractor={(item) => item.nregistro}
+        renderItem={({ item }) => <MedicineCard medicine={item} />}
+        contentContainerStyle={styles.list}
+        showsVerticalScrollIndicator={false}
+      />
     </View>
   );
 }
@@ -12,18 +80,27 @@ export default function HomeScreen() {
 const styles = StyleSheet.create({
   container: {
     flex: 1,
-    justifyContent: 'center',
+    backgroundColor: colors.background,
+  },
+  list: {
+    paddingBottom: spacing.xl,
+  },
+  errorContainer: {
+    padding: spacing.md,
+    marginHorizontal: spacing.md,
+    backgroundColor: '#F8D7DA',
+    borderRadius: 8,
+  },
+  errorText: {
+    color: '#721C24',
+    textAlign: 'center',
+  },
+  emptyContainer: {
+    padding: spacing.xl,
     alignItems: 'center',
-    backgroundColor: '#F2F2F7',
   },
-  title: {
-    fontSize: 28,
-    fontWeight: 'bold',
-    color: '#1C1C1E',
-  },
-  subtitle: {
+  emptyText: {
+    color: colors.textSecondary,
     fontSize: 16,
-    color: '#8E8E93',
-    marginTop: 8,
   },
 });