refactor: remove needless return in display_message error classification

Address CodeRabbit feedback on PR #725: the first branch in the
display_message() error classification chain had an early return while
the other branches did not. Rather than adding returns to all branches
(which clippy flags as needless_return since they're at the end of the
function), remove the inconsistent one. The else-if chain already
prevents fall-through, making the return redundant.

Both display_message() and display_task_result() now use a consistent
pattern: set self.error and let the else-if chain handle exclusivity.

Author: thepastaclaw

src/ui/dashpay/contact_requests.rs

@@ -1046,7 +1046,6 @@ impl ScreenLike for ContactRequests {
         if matches!(message_type, MessageType::Error | MessageType::Warning) {
             if message.contains("Recipient does not have") {
                 self.error = Some(DashPayError::RecipientMissingKey);
-                return;
             } else if message.contains("ENCRYPTION key") {
                 self.error = Some(DashPayError::MissingEncryptionKey);
             } else if message.contains("DECRYPTION key") {