feat(a11y): label icon-only buttons and inputs for screen readers

Header, message action, send/stop, history, model selector and dark-mode controls had no accessible name (icon-only buttons). Adds roles/labels and selected/disabled state; no visual change.

components/chat/ChatInput.tsx

@@ -65,7 +65,12 @@ export function ChatInput({ onSend, onStop, isLoading, editingText, onCancelEdit
             {isEditing && (
                 <View style={[styles.editBanner, { backgroundColor: colors.bannerBg, borderBottomColor: colors.border }]}>
                     <Text style={[styles.editBannerText, { color: colors.bannerText }]}>Editing message</Text>
-                    <TouchableOpacity onPress={handleCancelEdit} style={styles.editCancelBtn}>
+                    <TouchableOpacity
+                        onPress={handleCancelEdit}
+                        style={styles.editCancelBtn}
+                        accessibilityRole="button"
+                        accessibilityLabel="Cancel editing"
+                    >
                         <X size={16} color={colors.textMuted} />
                     </TouchableOpacity>
                 </View>
@@ -80,6 +85,7 @@ export function ChatInput({ onSend, onStop, isLoading, editingText, onCancelEdit
                     <TextInput
                         style={[styles.input, { color: colors.text }]}
                         placeholder="Send a message..."
+                        accessibilityLabel="Message"
                         placeholderTextColor={colors.textMuted}
                         value={text}
                         onChangeText={setText}
@@ -94,6 +100,8 @@ export function ChatInput({ onSend, onStop, isLoading, editingText, onCancelEdit
                             style={[styles.stopButton, { backgroundColor: colors.errorText }]}
                             onPress={handleStop}
                             activeOpacity={0.7}
+                            accessibilityRole="button"
+                            accessibilityLabel="Stop generating"
                         >
                             <Square size={16} color={colors.backgroundColor} />
                         </TouchableOpacity>
@@ -106,6 +114,9 @@ export function ChatInput({ onSend, onStop, isLoading, editingText, onCancelEdit
                             onPress={handleSend}
                             disabled={!text.trim()}
                             activeOpacity={0.7}
+                            accessibilityRole="button"
+                            accessibilityLabel="Send message"
+                            accessibilityState={{ disabled: !text.trim() }}
                         >
                             <Send size={18} color={text.trim() ? colors.backgroundColor : colors.textMuted} />
                         </TouchableOpacity>

components/chat/CodeBlock.tsx

@@ -16,7 +16,11 @@ export function CodeBlock({ language, content, copied, onCopy }: CodeBlockProps)
         <View style={styles.codeBlockWrapper}>
             <View style={styles.codeBlockHeader}>
                 <Text style={styles.codeBlockLanguage}>{language}</Text>
-                <TouchableOpacity onPress={() => onCopy(content)} style={styles.copyButton}>
+                <TouchableOpacity
+                    onPress={() => onCopy(content)}
+                    style={styles.copyButton}
+                    accessibilityRole="button"
+                >
                     <CopyIcon size={14} color="#A0A0A0" />
                     <Text style={styles.copyText}>{copied ? 'Copied!' : 'Copy'}</Text>
                 </TouchableOpacity>

components/chat/MessageActions.tsx

@@ -50,24 +50,24 @@ export function MessageActions({
 
     return (
         <View style={[styles.container, isUser ? styles.containerUser : styles.containerAssistant]}>
-            <TouchableOpacity style={styles.actionBtn} onPress={handleCopy} activeOpacity={0.6}>
+            <TouchableOpacity style={styles.actionBtn} onPress={handleCopy} activeOpacity={0.6} accessibilityRole="button" accessibilityLabel="Copy message">
                 <Copy size={16} color={colors.textMuted} />
             </TouchableOpacity>
 
             {isUser && onEdit && (
-                <TouchableOpacity style={styles.actionBtn} onPress={handleEdit} activeOpacity={0.6}>
+                <TouchableOpacity style={styles.actionBtn} onPress={handleEdit} activeOpacity={0.6} accessibilityRole="button" accessibilityLabel="Edit message">
                     <Pencil size={16} color={colors.textMuted} />
                 </TouchableOpacity>
             )}
 
             {!isUser && onRegenerate && (
-                <TouchableOpacity style={styles.actionBtn} onPress={handleRegenerate} activeOpacity={0.6}>
+                <TouchableOpacity style={styles.actionBtn} onPress={handleRegenerate} activeOpacity={0.6} accessibilityRole="button" accessibilityLabel="Regenerate response">
                     <RefreshCw size={16} color={colors.textMuted} />
                 </TouchableOpacity>
             )}
 
             {onDelete && (
-                <TouchableOpacity style={styles.actionBtn} onPress={handleDelete} activeOpacity={0.6}>
+                <TouchableOpacity style={styles.actionBtn} onPress={handleDelete} activeOpacity={0.6} accessibilityRole="button" accessibilityLabel="Delete message">
                     <Trash2 size={16} color={colors.textMuted} />
                 </TouchableOpacity>
             )}

components/chat/ModelSelector.tsx

@@ -42,6 +42,8 @@ export function ModelSelector() {
                 style={[styles.headerButton, { backgroundColor: colors.cardBackground }]}
                 onPress={() => setModalVisible(true)}
                 activeOpacity={0.7}
+                accessibilityRole="button"
+                accessibilityLabel={`Model: ${activeModelName}. Tap to change`}
             >
                 <ConnectionBadge isConnected={isConnected} compact />
                 <Text style={[styles.headerText, { color: colors.text }]} numberOfLines={1}>
@@ -70,6 +72,8 @@ export function ModelSelector() {
                                 onPress={handleRefresh}
                                 style={[styles.refreshButton, { backgroundColor: colors.cardBackground }]}
                                 disabled={isRefreshing}
+                                accessibilityRole="button"
+                                accessibilityLabel="Refresh models"
                             >
                                 {isRefreshing ? (
                                     <ActivityIndicator size="small" color={colors.textMuted} />
@@ -108,6 +112,9 @@ export function ModelSelector() {
                                             isSelected && { borderColor: colors.tint }
                                         ]}
                                         onPress={() => handleSelect(item.id)}
+                                        accessibilityRole="button"
+                                        accessibilityLabel={item.id}
+                                        accessibilityState={{ selected: isSelected }}
                                     >
                                         <View style={styles.itemContent}>
                                             <Text style={[styles.itemName, { color: colors.text }]}>

components/settings/AppearanceCard.tsx

@@ -29,6 +29,7 @@ export function AppearanceCard() {
                 <Switch
                     value={isDarkMode}
                     onValueChange={toggleTheme}
+                    accessibilityLabel="Dark Mode"
                     trackColor={{ false: '#E2E8F0', true: colors.tint }}
                     thumbColor={'#FFFFFF'}
                 />