zsh:keys: Modify fzf's cd widget to be "in-prompt"

Currently, fzf's cd widget executes the cd command via accept-line, so
the command is also visible in the scrollback buffer. In contrast to
this, the cd-{forward,backward,up} suite changes the directory in-place,
without touching BUFFER, with an additional prompt redraw (one could say
"in-prompt"). Since I find this more appealing, overwrite the default
fzf widget with a custom one that has the same behaviour.

.config/zsh/zshrc.d/60-keys.zsh

@@ -126,6 +126,27 @@ function cd-up {
 }
 zle -N cd-up
 
+# Modified version of
+# https://github.com/junegunn/fzf/blame/f864f8b5f7ab/shell/key-bindings.zsh#L81-L99
+# that changes the directory "in-prompt" like cd-{forward,backward,up}; meaning
+# that the `cd` command is executed in the background with a prompt redraw
+# instead of via `$BUFFER` and `accept-line`.
+fzf-cd-inprompt-widget() {
+	setopt localoptions pipefail no_aliases 2>/dev/null
+	local dir="$(
+		FZF_DEFAULT_COMMAND=${FZF_ALT_C_COMMAND:-} \
+		FZF_DEFAULT_OPTS=$(__fzf_defaults "--reverse --walker=dir,follow,hidden --scheme=path" "${FZF_ALT_C_OPTS-} +m") \
+		FZF_DEFAULT_OPTS_FILE='' $(__fzfcmd) < /dev/tty)"
+	if [[ -z "$dir" ]]; then
+		zle redisplay
+		return 0
+	fi
+	# --- modifications start here ---
+	pushd -q "$dir"
+	redraw-prompt
+}
+zle -N fzf-cd-inprompt-widget
+
 # cycle through `dirs` with ^o and ^i similar to the jumplist in vim.
 # Need AUTO_PUSHD (see options.zsh)
 bindkey '^O' cd-backward
@@ -256,3 +277,7 @@ FZF_CTRL_T_COMMAND="${FZF_DEFAULT_COMMAND} 2>/dev/null"
 
 # See .zprofile for FZF_ALT_C_COMMAND
 comp-source "$ZDOTDIR/plugins/fzf/shell/key-bindings.zsh"
+
+# Overwrite fzf's Alt-C binding to be "in-prompt" (see above)
+bindkey -M vicmd '\ec' fzf-cd-inprompt-widget
+bindkey -M viins '\ec' fzf-cd-inprompt-widget