Update employment 1-year data for 2024

[jwalsh28]

This PR updates the employment metric with 2024 data

Main changes are:

1. Update the dates in the QMD files to read in 2024
2. Fix an issue with the IPUMS pull function because of a changed variable name
3. Create a subfolder to organize single year HTLM output files

[malcalakovalski]

This looks good to me! I do think 90% of the code seems similar across .qmd files and I wonder if this metric could benefit from a single parametrized quarto doc. Alternatively, the common logic across the docs could be extracted into functions in 09_employment/R/ (data cleaning, validation, etc.).

Also, out of curiosity, what model did you use for the AI documentation?

I also think using urbnthemes for consistency with the rest of the plots in this project would be good!