Handle error states and accessibility improvements

src/components/form/ManualSearchInput.js

@@ -3,20 +3,21 @@ import { StyleSheet, TextInput, View } from 'react-native';
 import PrimaryButton from '../PrimaryButton';
 import { colors } from '../../utils/constants';
 
-export default function ManualSearchInput({ value, onChangeText, onSubmit, placeholder = 'Produktname oder Barcode' }) {
+export default function ManualSearchInput({ value, onChangeText, onSubmit, disabled = false, placeholder = 'Produktname oder Barcode' }) {
   return (
     <View style={styles.row}>
       <TextInput
         autoCapitalize="none"
         onChangeText={onChangeText}
         onSubmitEditing={onSubmit}
+        editable={!disabled}
         placeholder={placeholder}
         placeholderTextColor={colors.muted}
         returnKeyType="search"
         style={styles.input}
         value={value}
       />
-      <PrimaryButton label="Suchen" onPress={onSubmit} />
+      <PrimaryButton disabled={disabled} label="Suchen" onPress={onSubmit} />
     </View>
   );
 }

src/components/layout/AppHeader.js

@@ -7,7 +7,7 @@ export default function AppHeader({ title, subtitle, onBack, rightAction }) {
     <View style={styles.header}>
       <View style={styles.row}>
         {onBack ? (
-          <Pressable accessibilityRole="button" onPress={onBack} style={styles.backButton}>
+          <Pressable accessibilityLabel="Zurück" accessibilityRole="button" onPress={onBack} style={styles.backButton}>
             <Text style={styles.backText}>‹</Text>
           </Pressable>
         ) : null}

src/components/layout/BottomTabBar.js

@@ -16,6 +16,7 @@ export default function BottomTabBar({ activeTab, onChange }) {
         const isActive = activeTab === tab.id;
         return (
           <Pressable
+            accessibilityLabel={`${tab.label} öffnen`}
             accessibilityRole="button"
             key={tab.id}
             onPress={() => onChange(tab.id)}