fix: enable user to press Enter in signup flow

frontend/src/components/signup/CodeInputStep.tsx

@@ -114,6 +114,7 @@ export default function CodeInputStep({
       <div className="flex flex-col items-center justify-center lg:w-[19%] w-1/4 min-w-[20rem] mt-2 max-w-xs md:max-w-md mx-auto text-sm text-center md:text-left">
         <div className="text-l py-1 text-lg w-full">
           <Button
+            type="submit"
             onClick={incrementStep}
             size="sm"
             isFullWidth

frontend/src/components/signup/EnterEmailStep.tsx

@@ -70,6 +70,7 @@ export default function EnterEmailStep({
         <div className="flex flex-col items-center justify-center lg:w-1/6 w-1/4 min-w-[20rem] mt-2 max-w-xs md:max-w-md mx-auto text-sm text-center md:text-left">
           <div className="text-l py-1 text-lg w-full">
             <Button
+              type="submit"
               onClick={emailCheck}
               size="sm"
               isFullWidth

frontend/src/components/signup/UserInfoStep.tsx

@@ -248,7 +248,6 @@ export default function UserInfoStep({
             placeholder=""
             onChange={(e) => setAttributionSource(e.target.value)}
             value={attributionSource}
-            isRequired
             className="h-12"
           />
         </div>
@@ -301,6 +300,7 @@ export default function UserInfoStep({
         <div className="flex flex-col items-center justify-center lg:w-[19%] w-1/4 min-w-[20rem] mt-2 max-w-xs md:max-w-md mx-auto text-sm text-center md:text-left">
           <div className="text-l py-1 text-lg w-full">
             <Button
+              type="submit"
               onClick={signupErrorCheck}
               size="sm"
               isFullWidth