Utility function to convert a Unix timestamp (seconds since 1970-01-01 UTC)
into a POSIXct object.
Uses lubridate::as_datetime() for readability and consistency with the
tidyverse ecosystem.
Examples
# Single timestamp
whapi_to_posixct(1756426418)
#> [1] "2025-08-29 00:13:38 UTC"
# Vector of timestamps (with NA)
whapi_to_posixct(c(1756426418, NA))
#> [1] "2025-08-29 00:13:38 UTC" NA
# Character input
whapi_to_posixct("1756426418")
#> [1] "2025-08-29 00:13:38 UTC"
