fix(app): auto-grow text input on iOS

Remove explicit height style on iOS TextInput - only use minHeight/maxHeight
to allow native auto-sizing. Web still uses explicit height for controlled
sizing via onContentSizeChange measurement.

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

packages/app/src/components/message-input.tsx

@@ -491,14 +491,19 @@ export const MessageInput = forwardRef<MessageInputRef, MessageInputProps>(
           placeholderTextColor={theme.colors.mutedForeground}
           style={[
             styles.textInput,
-            {
+            IS_WEB
-              height: inputHeight,
+              ? {
-              minHeight: MIN_INPUT_HEIGHT,
+                  height: inputHeight,
-              maxHeight: MAX_INPUT_HEIGHT,
+                  minHeight: MIN_INPUT_HEIGHT,
-            },
+                  maxHeight: MAX_INPUT_HEIGHT,
+                }
+              : {
+                  minHeight: MIN_INPUT_HEIGHT,
+                  maxHeight: MAX_INPUT_HEIGHT,
+                },
           ]}
           multiline
-          scrollEnabled={inputHeight >= MAX_INPUT_HEIGHT}
+          scrollEnabled={IS_WEB ? inputHeight >= MAX_INPUT_HEIGHT : true}
           onContentSizeChange={handleContentSizeChange}
           editable={!isDictating && isConnected && !disabled}
           onKeyPress={