zsh:keys: Fix override of fzf-cd-widget

This commit addresses a couple of issues:

1. fzf's `key-bindings.zsh` was sourced twice: Once in keys.zsh and once
   via the symlink in `external-plugins/`. Fix this by removing the
   source in `keys.zsh`.

2. The section about the fzf bindings in keys.zsh was a mess. Reorder
   and rewrite some comments to make it nicer.

3. My just added custom `fzf-cd-inplace-widget` does not work like this.
   Since `key-bindings.zsh` is sourced (was sourced again) after
   `keys.zsh`, my override is overridden itself by the default. I
   noticed and fixed this when I originally wrote and tested the
   function, but unfortunately I forgot the old `bindkey` commands in
   `keys.zsh`, which is why I now forgot about it and committed this
   erroneously. To fix this, bind the keys after sourcing
   `key-binding.zsh` in the newly added `fzf.key-bindings.config.zsh`.
   Additionally, move the widget definition as well to have everything
   at one place.

Fixes: 3cf445e739 (zsh:keys: Modify fzf's cd widget to be "in-prompt",
       2025-08-06)

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

@@ -126,27 +126,6 @@ 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
@@ -269,15 +248,15 @@ bindkey '^[[1;5A' fzf-history-widget
 bindkey -M vicmd '^K' fzf-history-widget
 
 # Fuzzy finder bindings:
-# ^T fzf-file-widget
-# \ec (Alt-C) fzf-cd-widget
-# ^R fzf-history-widget
-# TODO: ^R should insert the history line in BUFFER to differ from ctrl-up
+#
+# - ^T fzf-file-widget
+# - \ec (Alt-C) fzf-cd-widget
+# - ^R fzf-history-widget
+#
+# are sourced via 90-external-plugins/50-fzf.key-bindings.zsh, but see also
+# 55-fzf.key-bindings.config.zsh
+
+# Discard stderr (i.e. permission denied)
 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
+# TODO: ^R should insert the history line in BUFFER to differ from ctrl-up