fix: restore #[test] attributes on parse_no_args, peer_receives_op_encoded_via_wire_codec, keepalive_constants_are_correct

Same root cause as 0d805313: when extracting a test that's the FIRST inside its
mod block, the slicer started at the fn line and missed the leading #[test]
attribute on the previous line. Test count now matches pre-split count (2636).

server/src/cli.rs

@@ -178,6 +178,7 @@ pub(crate) fn resolve_path_arg(path_str: Option<&str>, cwd: &std::path::Path) ->
 mod tests {
     use super::*;
 
+    #[test]
     fn parse_no_args() {
         let result = parse_cli_args(&[]).unwrap();
         assert_eq!(result.port, None);