should we change from `gender` to `sex` to homogenize with {simulist}?

tagging @joshwlambert as I heard from you that you received feedback on this. found this reported in the [changelog](https://epiverse-trace.github.io/simulist/news/#breaking-changes-0-2-0)

this would also avoid misunderstandings when connecting simulist with linelist

``` r
simulist::sim_linelist() |> names()
#> [1] "id" "case_name" "case_type"
#> [4] "sex" "age" "date_onset"
#> [7] "date_reporting" "date_admission" "outcome"
#> [10] "date_outcome" "date_first_contact" "date_last_contact"
#> [13] "ct_value"
linelist::tags_names()
#> [1] "id" "date_onset" "date_reporting" "date_admission"
#> [5] "date_discharge" "date_outcome" "date_death" "gender"
#> [9] "age" "location" "occupation" "hcw"
#> [13] "outcome"
```

^{Created on 2025-07-03 with [reprex v2.1.1](https://reprex.tidyverse.org)}

Start by comparing the linked simulist changelog with the public output of linelist::tags_names(), then locate the implementation and tests behind that entry point. Determine the scope and compatibility impact of replacing gender with sex, and consider the work done only when the naming decision is implemented consistently and verified by the relevant tests.

Written by the indexing model from the issue text.