Fix {.help} markup to use correct cli link format [{.fun fn}](AMR::fn)

Replace all instances of {.help AMR::fn}() (incorrect format with manual
parentheses outside the link) with {.help [{.fun fn}](AMR::fn)} which is
the correct cli hyperlink syntax: the display text [{.fun fn}] renders the
function name with parentheses automatically, and (AMR::fn) is the link target.

Also update the plain-text fallback handler in aa_helper_functions.R to
extract the display text from the [text](topic) markdown link format,
so that non-cli environments show just the function name (e.g. `fn()`),
not the raw link markup.

Dynamic cases in amr_selectors.R and mo_property.R also updated.

https://claude.ai/code/session_01XHWLohiSTdZvCutwD7ag2b

R/amr_selectors.R

@@ -837,7 +837,7 @@ amr_select_exec <- function(function_name,
 #' @export
 #' @noRd
 print.amr_selector <- function(x, ...) {
-  warning_("It should never be needed to print an antimicrobial selector class. Are you using {.pkg data.table}? Then add the argument {.code with = FALSE}, see our examples at {.help AMR::amr_selector}().",
+  warning_("It should never be needed to print an antimicrobial selector class. Are you using {.pkg data.table}? Then add the argument {.code with = FALSE}, see our examples at {.help [{.fun amr_selector}](AMR::amr_selector)}.",
     immediate = TRUE
   )
   cat("Class 'amr_selector'\n")
@@ -1062,7 +1062,7 @@ message_agent_names <- function(function_name, agents, ab_group = NULL, examples
   if (message_not_thrown_before(function_name, sort(agents))) {
     if (length(agents) == 0) {
       if (is.null(ab_group)) {
-        message_("For {.help AMR::", function_name, "}() no antimicrobial drugs found", examples, ".")
+        message_("For {.help [{.fun ", function_name, "}](AMR::", function_name, ")} no antimicrobial drugs found", examples, ".")
       } else if (ab_group == "administrable_per_os") {
         message_("No orally administrable drugs found", examples, ".")
       } else if (ab_group == "administrable_iv") {