fix(spec): harden bash completion mock for non-tty runs

The mock never had a real terminal to fall back to, so two latent
bash-completion quirks surfaced as test failures:

- Interactive bash expanded `!` in `_filedir`'s xspec, breaking the
  extension filter for `apply --file ...`.
- An unset `COLUMNS` collapsed `__cli1_format_comp_descriptions` into
  bare names, so `-e dev ""` lost its description columns.

Disable history expansion, default `COLUMNS` to a wide value, and patch
`_filedir` to handle the empty-`cur` case the way real bash does via
`complete -o default`.

Author: claude

src/tabular/shell/bash.ecr

@@ -1,10 +1,38 @@
+# History expansion turns the `!` in `_filedir`'s xspec into a syntax error and
+# leaves descriptions unformatted when `COLUMNS` is unset, so harden both up
+# front before any completion machinery is loaded.
+set +H
+export COLUMNS="${COLUMNS:-200}"
+
 <% {% if flag?(:darwin) %} -%>
 init="/opt/homebrew/etc/profile.d/bash_completion.sh"
 <% {% end %} -%>
 <% {% if flag?(:linux) %} -%>
 init="/etc/profile.d/bash_completion.sh"
 <%- {% end %} -%>
 [[ -f "${init}" ]] && . "${init}"
+
+# Patch `_filedir` so an empty `cur` still expands extension filters. Stock
+# bash-completion routes empty cur through `_quote_readline_by_ref`, which
+# yields the literal `''` and then matches no files; real bash papers over
+# this with `complete -o default`, but the mock has no shell to fall back to.
+if declare -F _filedir >/dev/null 2>&1; then
+	eval "__tabular_orig_filedir() $(declare -f _filedir | tail -n +2)"
+	_filedir() {
+		if [[ -z ${cur-} && -n ${1-} && ${1-} != "-d" ]]; then
+			local __xspec="!*.@(${1}|${1^^})"
+			local __reset
+			__reset=$(shopt -po noglob)
+			set -o noglob
+			COMPREPLY+=( $(compgen -f -X "$__xspec" -o plusdirs -- "") )
+			$__reset
+			(( ${#COMPREPLY[@]} > 0 )) && compopt -o filenames 2>/dev/null
+			return 0
+		fi
+		__tabular_orig_filedir "$@"
+	}
+fi
+
 <% completers.each do |comp| -%>
 eval "$(<%= comp %> completion <%= bin %>)"
 <% end %>