fix(asdf)!: remove legacy <0.16 integration

`asdf` plugin only supports asdf 0.16 and ahead from now on.

plugins/asdf/asdf.plugin.zsh

@@ -1,48 +1,13 @@
-if (( $+commands[asdf] )); then
-  export ASDF_DATA_DIR="${ASDF_DATA_DIR:-$HOME/.asdf}"
-  path=("$ASDF_DATA_DIR/shims" $path)
+(( ! $+commands[asdf] )) && return
 
-  # If the completion file doesn't exist yet, we need to autoload it and
-  # bind it to `asdf`. Otherwise, compinit will have already done that.
-  if [[ ! -f "$ZSH_CACHE_DIR/completions/_asdf" ]]; then
-    typeset -g -A _comps
-    autoload -Uz _asdf
-    _comps[asdf]=_asdf
-  fi
-  asdf completion zsh >| "$ZSH_CACHE_DIR/completions/_asdf" &|
+export ASDF_DATA_DIR="${ASDF_DATA_DIR:-$HOME/.asdf}"
+path=("$ASDF_DATA_DIR/shims" $path)
 
-  return
-fi
-
-# TODO:(2025-02-12): remove deprecated asdf <0.16 code
-
-# Find where asdf should be installed
-ASDF_DIR="${ASDF_DIR:-$HOME/.asdf}"
-ASDF_COMPLETIONS="$ASDF_DIR/completions"
-
-if [[ ! -f "$ASDF_DIR/asdf.sh" || ! -f "$ASDF_COMPLETIONS/_asdf" ]]; then
-  # If not found, check for archlinux/AUR package (/opt/asdf-vm/)
-  if [[ -f "/opt/asdf-vm/asdf.sh" ]]; then
-    ASDF_DIR="/opt/asdf-vm"
-    ASDF_COMPLETIONS="$ASDF_DIR"
-  # If not found, check for Homebrew package
-  elif (( $+commands[brew] )); then
-    _ASDF_PREFIX="$(brew --prefix asdf)"
-    ASDF_DIR="${_ASDF_PREFIX}/libexec"
-    ASDF_COMPLETIONS="${_ASDF_PREFIX}/share/zsh/site-functions"
-    unset _ASDF_PREFIX
-  else
-    return
-  fi
-fi
-
-# Load command
-if [[ -f "$ASDF_DIR/asdf.sh" ]]; then
-  source "$ASDF_DIR/asdf.sh"
-  # Load completions
-  if [[ -f "$ASDF_COMPLETIONS/_asdf" ]]; then
-    fpath+=("$ASDF_COMPLETIONS")
-    autoload -Uz _asdf
-    compdef _asdf asdf # compdef is already loaded before loading plugins
-  fi
+# If the completion file doesn't exist yet, we need to autoload it and
+# bind it to `asdf`. Otherwise, compinit will have already done that.
+if [[ ! -f "$ZSH_CACHE_DIR/completions/_asdf" ]]; then
+  typeset -g -A _comps
+  autoload -Uz _asdf
+  _comps[asdf]=_asdf
 fi
+asdf completion zsh >| "$ZSH_CACHE_DIR/completions/_asdf" &|