immediateCondition on delayed tasks

**Describe the bug**

Similar to https://github.com/futureverse/future.mirai/issues/17, I'm adapting `immediateMessage` as mentioned in https://github.com/futureverse/progressr/issues/176 for `multisession`.

It seems to work for the initial tasks, but others require an attempt to realize the value before it is printed.

**Reproduce example**

I'll source all of this code first. Since I'm starting two workers, the `x` and `y` expressions start immediately, and the third is intended to be queued and will process when the first two clear.

```r
immediateMessage <- function (..., domain = NULL, appendLF = TRUE) {
# prepend the time, perhaps sloppy but good for demonstration
msg <- .makeMessage(c(format(Sys.time()), " ", ...), domain = domain, appendLF = appendLF)
call <- sys.call()
cond <- simpleMessage(msg, call)
class(cond) <- c(class(cond), "immediateCondition")
message(cond)
}

library(future)
plan(multisession, workers=2)
x %<-% { immediateMessage("in x"); Sys.sleep(2); immediateMessage(paste("x ", Sys.getpid())); Sys.sleep(2); 3.14 }
y %<-% { immediateMessage("in y"); Sys.sleep(2); immediateMessage(paste("y ", Sys.getpid())); Sys.sleep(2); 2.71 }
z %<-% { immediateMessage("in z"); Sys.sleep(2); immediateMessage(paste("z ", Sys.getpid())); Sys.sleep(2); 1.62 }
x+y
```

If I source that block, then I see

```r
library(future)
plan(multisession, workers=2)
x %<-% { immediateMessage("in x"); Sys.sleep(2); immediateMessage(paste("x ", Sys.getpid())); Sys.sleep(2); 3.14 }
y %<-% { immediateMessage("in y"); Sys.sleep(2); immediateMessage(paste("y ", Sys.getpid())); Sys.sleep(2); 2.71 }
z %<-% { immediateMessage("in z"); Sys.sleep(2); immediateMessage(paste("z ", Sys.getpid())); Sys.sleep(2); 1.62 }
# 2025-01-31 11:41:22 in x
# 2025-01-31 11:41:22 in y
# 2025-01-31 11:41:24 x 9219
# 2025-01-31 11:41:24 y 9218
x+y
# [1] 5.85
```

As I said in the other issue, the fact that `x+y` shows _after_ the messages indicates that some messages are immediate.

Once that's done, I pause for a moment and see that the `z` messages do not appear. If I then manually type `z` in the console, I _immediately_ see:

```r
z; Sys.time()
# 2025-01-31 11:41:26 in z
# 2025-01-31 11:41:28 z 9219
# [1] 1.62
# [1] "2025-01-31 11:42:25 EST"
```

It is clear to me that the execution was in fact scheduled immediately after one of `x` or `y` completed, but the messages themselves did not appear until I evaluated `z` (and the `11:42:25` indicates the time between when I pasted here, then typed some comments, and then went back to the console, demonstrating that the `z` code executed correctly on time).

A reproducible example using R code.

Please format your inline code and code blocks using Markdown ().

**Expected behavior**

I expect the `z` messages would appear on the console immediately after one of the `x` or `y` tasks is complete.

**Session information**

sessionInfo()

R version 4.3.3 (2024-02-29)

Platform: aarch64-apple-darwin20 (64-bit)

Running under: macOS 15.2


Matrix products: default

BLAS:   /Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/lib/libRblas.0.dylib 

LAPACK: /Library/Frameworks/R.framework/Versions/4.3-arm64/Resources/lib/libRlapack.dylib;  LAPACK version 3.11.0

locale:

[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

time zone: America/New_York

tzcode source: internal

attached base packages:

[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:

[1] future.mirai_0.2.2 future_1.34.0      r2_0.12.0         

loaded via a namespace (and not attached):

 [1] mirai_2.0.1       digest_0.6.37     codetools_0.2-20  fastmap_1.2.0     xfun_0.49         nanonext_1.5.0    knitr_1.49        parallel_4.3.3    htmltools_0.5.8.1

[10] rmarkdown_2.29    cli_3.6.3         parallelly_1.40.1 compiler_4.3.3    globals_0.16.3    tools_4.3.3       listenv_0.9.1     clipr_0.8.0       evaluate_1.0.1   

[19] rlang_1.1.5