Fix request_id mismatch causing 5s hang on every PUT commit

The COMMIT_PUT message was built with request_id N, then request_id
was incremented to N+1 immediately after sending. When the server
replied with request_id N, the client compared it against N+1,
silently discarded the reply, and waited for the 5-second timeout.
The timeout retry (replay_request) then resent with N+1, which
matched — so every PUT paid an unnecessary 5-second penalty.

Move the request_id++ before building the CommitPutMessage, matching
the pattern already used by toastyfs_async_delete.

https://claude.ai/code/session_01EG3WZSH3ZeTdAbb5T42r2w

src/client.c

@@ -455,6 +455,7 @@ static int process_message(ToastyFS *tfs,
                     begin_transfers(tfs);
                     if (all_chunk_transfers_completed(tfs)) {
 
+                        tfs->request_id++;
                         CommitPutMessage msg = {
                             .base = {
                                 .version = MESSAGE_VERSION,
@@ -477,7 +478,6 @@ static int process_message(ToastyFS *tfs,
                             msg.oper.chunks[i].size = tfs->chunk_sizes[i];
                         }
                         send_message_to_server(tfs, leader_idx(tfs), &msg.base);
-                        tfs->request_id++;
                         tfs->step = STEP_COMMIT;
                         client_log(tfs, "SEND COMMIT_PUT", "key=%s chunks=%d req=%lu",
                             tfs->key, tfs->num_chunks, tfs->request_id);