feat(shell): major refactor around history and completion setup

Biggest change is embracing fzf for all shell completion. This includes
using tmux popup windows to effectively render completions as floating
popups with fuzzy matching via fzf.

Shell history has also been improved, with appending each command to the
history file one by one, rather than only at end of a shell session when
the shell exists. This should ensure I don't have any more lost commands
cause the shell didn't exit cleanly.

zsh/fzf.zsh

@@ -1,18 +0,0 @@
-#
-# fzf
-#
-
-export FZF_CTRL_T_OPTS="--preview='less {}'"
-export FZF_DEFAULT_OPTS="--bind=ctrl-k:kill-line --border=none --tabstop=4"
-export FZF_TMUX=0
-export FZF_TMUX_HEIGHT=100%
-
-# Install fzf binary from latest GitHub Release.
-zinit light-mode wait lucid from'gh-r' as'program' pick'fzf' \
-  for @junegunn/fzf
-
-# Install fzf-tmux command and zsh plugins from default branch on GitHub.
-zinit light-mode wait lucid from'gh' as'program' pick'bin/fzf-tmux' \
-  multisrc'shell/{completion,key-bindings}.zsh' \
-  id-as'junegunn/fzf-extras' \
-  for @junegunn/fzf

zsh/ruby.zsh

@@ -2,6 +2,13 @@
 # Ruby environment setup.
 #
 
+# ==============================================================================
+# bundler
+# ==============================================================================
+
+# Enable Ruby Bundler plugin from oh-my-zsh.
+zinit for @OMZ::plugins/bundler
+
 # ==============================================================================
 # aliases
 # ==============================================================================

zsh/zshrc.funcs.zsh

@@ -1,5 +1,5 @@
 #
-# Interactive Utility Functions
+# zshrc helper functions
 #
 # Helpers designed for use during setup of interactive shell environments
 # (~/.zshrc ).
@@ -36,32 +36,32 @@
 setup-completions() {
   local cmd="$1"
   local source="$2"
-  local setup_cmd="$3"
-  shift 3
+  shift 2
+  local script="$@"
 
   local target_dir="${ZSH_COMPLETIONS:-$HOME/.zsh/completions}"
   local target_file="${target_dir}/_${cmd}"
 
+  if [[ -z "$cmd" || -z "$source" || -z "$script" ]]; then
+    echo "setup-completions: Missing required arguments." >&2
+    return 1
+  fi
+
   if [[ -z "$(command -v "$cmd")" ]]; then
     echo "setup-completions: Command not found: $cmd" >&2
     return 1
   fi
 
-  if [[ -z "$(command -v "$setup_cmd")" ]]; then
-    echo "setup-completions: Command not found: $setup_cmd" >&2
-    return 1
-  fi
-
-  if [[ -z "$cmd" || -z "$source" || -z "$setup_cmd" ]]; then
-    echo "setup-completions: Missing required arguments." >&2
+  if [[ -z "$source" ]]; then
+    echo "setup-completions: Source file not found: $source" >&2
     return 1
   fi
 
   # Check if the target completion file needs to be updated
   if [[ ! -f "$target_file" || "$source" -nt "$target_file" ]]; then
-    echo "setup-completions: Setting up completion for $cmd --> $target_file" >&2
+    echo "setup-completions: Setting up completion for $cmd: $script" >&2
     mkdir -p "$target_dir"
-    "$setup_cmd" "$@" >| "$target_file"
+    eval "$script" >| "$target_file"
     chmod +x "$target_file"
 
     # Only run compinit if not already loaded