Medications updates + new variable names

[rafdoodle]

Hello Doug,

Hope you are doing well. I have updated the last code chunk of recoding-medications.qmd to explain the derivation and use of anymed2 and 'diab_drug2 as intermediate medication variables. Such variables are duplicated from anymed and 'diab_drug and used to recode hypertension and diabetes, respectively, without the need of:

• listing many required raw variables (atc_101a, atc_102a, etc.) in a single rec_with_table() call
• using medication variables with multiple rows per respondent (meucatc and npi_25b)

I also deleted the Role column of variables.csv and made minor fixes to variable-details. Additionally, in the Variable naming section of AI.md, Claude and I derived new proposed snake_case names for all the derived variables of chmsflow.

Please let me know what you think.

Rafidul