[landing] Fix ConnectFarcaster

Summary: Addresses [ENG-9506](https://linear.app/comm/issue/ENG-9506/farcaster-login-issues). @horsefacts helped me out here. We should be waiting for `connect` to finish before calling `signIn`.

Test Plan: I tested the SIWF flow on Android following [this doc](https://www.notion.so/commapp/How-to-test-Farcaster-connect-screen-114d823c518b80cf9b10da4d961bc807)

Reviewers: varun, will

Reviewed By: varun

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13620

landing/connect-farcaster.react.js

@@ -41,12 +41,6 @@ function ConnectFarcaster(): React.Node {
     validSignature,
   } = signInState;
 
-  React.useEffect(() => {
-    if (!channelToken) {
-      connect();
-    }
-  }, [channelToken, connect]);
-
   const messageSentRef = React.useRef<boolean>(false);
   const authenticated = isSuccess && validSignature;
 
@@ -57,6 +51,8 @@ function ConnectFarcaster(): React.Node {
     if (isError) {
       messageSentRef.current = false;
       reconnect();
+    } else if (!channelToken) {
+      connect();
     }
 
     signIn();
@@ -69,7 +65,7 @@ function ConnectFarcaster(): React.Node {
         url: url.toString(),
       });
     }
-  }, [authenticated, isError, reconnect, signIn, url]);
+  }, [authenticated, isError, reconnect, channelToken, connect, signIn, url]);
 
   return null;
 }