Fix client timeout propagation and add operation retry logic

The client library had several issues preventing operations from completing
in the simulation:

- toastyfs_register_events discarded the computed timeout instead of
  returning it to callers, so clients never woke up on schedule
- random_client_tick ignored the timeout parameter entirely
- deadline_to_timeout truncated sub-millisecond values to 0 instead of
  rounding up, causing busy-wait loops
- The server didn't reset the heartbeat timer after completing a view
  change, so followers would immediately timeout again
- The client's DELETE handler didn't handle META_RESULT_NOT_FOUND,
  causing an assertion failure when deleting non-existent keys
- Most critically, messages sent before TCP connections were established
  were silently dropped with no retry mechanism — added timeout-based
  retry logic in toastyfs_process_events

https://claude.ai/code/session_0184gHjra7fsmSPZ4kppaGhC

include/toastyfs.h

@@ -33,7 +33,7 @@ ToastyFS *toastyfs_init(uint64_t client_id, char **addrs, int num_addrs);
 void toastyfs_free(ToastyFS *tfs);
 
 void toastyfs_process_events(ToastyFS *tfs, void **ctxs, struct pollfd *pdata, int pnum);
-int  toastyfs_register_events(ToastyFS *tfs, void **ctxs, struct pollfd *pdata, int pcap);
+int  toastyfs_register_events(ToastyFS *tfs, void **ctxs, struct pollfd *pdata, int pcap, int *timeout);
 
 int toastyfs_async_put(ToastyFS *tfs, char *key, int key_len,
     char *data, int data_len);