locate an object .rds file in the remake storr

```r
target_name <- 'your_target_name'
obj <- remake:::remake('remake.yml', verbose = FALSE, load_sources = FALSE, allow_missing_packages = TRUE)
rds_file <- file.path('.remake/objects/data', paste0(obj$store$objects$get_hash(target_name, 'objects'), '.rds'))
readRDS(rds_file)
```

Would be nice if this were a function in scipiper.

Start with the supplied remake.yml example and trace how remake's storr uses get_hash() to derive the path under .remake/objects/data. Define the scipiper function around that lookup, with completion meaning it can locate the requested target's .rds file consistently.

Written by the indexing model from the issue text.