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/resistance_predict.R

@@ -238,7 +238,7 @@ resistance_predict <- function(x,
     prediction <- predictmodel$fit
     se <- predictmodel$se.fit
   } else {
-    stop("no valid model selected. See {.help AMR::resistance_predict}().")
+    stop("no valid model selected. See {.help [{.fun resistance_predict}](AMR::resistance_predict)}.")
   }
 
   # prepare the output dataframe