Replace bare backticks with cli inline markup across all messaging calls

- {.arg} for argument names in stop_/warning_/message_ calls
- {.cls} after "of class" text in format_class() and elsewhere
- {.fun} for function names (replaces `fn()` pattern)
- {.pkg} for tidyverse package names (dplyr, ggplot2)
- {.code} for code literals (TRUE, FALSE, expressions)
- Rewrite print.ab: use cli named-vector with * bullets and code
  highlighting when cli >= 3.0.0; keep plain-text fallback otherwise
- Fix typo in as.sir(): "of must be" -> "or must be"
- switch sir.R verbose notes from message() to message_()

https://claude.ai/code/session_01XHWLohiSTdZvCutwD7ag2b

R/join_microorganisms.R

@@ -185,7 +185,7 @@ join_microorganisms <- function(type, x, by, suffix, ...) {
   }
 
   if (type %like% "full|left|right|inner" && NROW(joined) > NROW(x)) {
-    warning_("in `{type}_microorganisms()`: the newly joined data set contains {nrow(joined) - nrow(x)} rows more than the number of rows of {.arg x}.")
+    warning_("in {.fun {type}_microorganisms}: the newly joined data set contains {nrow(joined) - nrow(x)} rows more than the number of rows of {.arg x}.")
   }
 
   as_original_data_class(joined, class(x.bak)) # will remove tibble groups