Replace single-quoted literals in messaging calls with cli markup

Converted bare 'value' strings inside stop_(), warning_(), message_()
to appropriate cli markup:
- {.val}: option values ('drug', 'dose', 'administration', 'SDD', 'logbook')
- {.cls}: class names ('sir', 'mo')
- {.field}: column names ('mo' in mo_source)
- {.code}: object/dataset names ('clinical_breakpoints')

Files changed: ab_from_text.R, av_from_text.R, sir.R, sir_calc.R, mo_source.R

https://claude.ai/code/session_01XHWLohiSTdZvCutwD7ag2b

R/mo_source.R

@@ -289,7 +289,7 @@ check_validity_mo_source <- function(x, refer_to_name = "`reference_df`", stop_o
   }
   if (!"mo" %in% colnames(x)) {
     if (stop_on_error == TRUE) {
-      stop_(refer_to_name, " must contain a column 'mo'", call = FALSE)
+      stop_(refer_to_name, " must contain a column {.field mo}", call = FALSE)
     } else {
       return(FALSE)
     }