feat(cli): rsync short-option clustering and inline/attached values (#285)

Implement rsync 3.4.1 client-CLI parity:
- cluster boolean shorts (-av, -aAX, -rlpt) and accept attached values
  (-B1048576, -essh, -Mfoo); add the -r, -b, -L and -B short aliases
  (-r is a faithful no-op since FastSync is always recursive)
- stop OPT_NOOP (-s/--secluded-args, -r/--recursive) from swallowing the
  next argv
- add inline --opt=value for every value-taking long option, including
  --exclude/--include/--exclude-from/--include-from/--log-file (#291)
- accept --port on the server CLI in addition to -p (#296)
- reject unknown flags naming the flag and stating it is unsupported

Unit tests cover clustering, attached/inline values, the OPT_NOOP
argument-consumption fix and rejected shorts.

src/server/server.c

@@ -1051,7 +1051,7 @@ static void print_server_usage(void) {
   printf("  --early-input=FILE  Second credential store layered over\n");
   printf("                      --password-file (same format); usually a secrets-\n");
   printf("                      manager/process-substitution file.  Requires --daemon\n");
-  printf("  -p <port>           TCP port (default: 8080, range: 1-65535)\n");
+  printf("  -p, --port <port>   TCP port (default: 8080, range: 1-65535)\n");
   printf("  --tls               Enable TLS encryption\n");
   printf("  --cert <path>       TLS certificate file (PEM)\n");
   printf("  --key <path>        TLS private key file (PEM)\n");