feat: keep empty cells consistent empty

lib/mv_web/components/core_components.ex

@@ -300,6 +300,81 @@ defmodule MvWeb.CoreComponents do
   defp badge_style_class("outline"), do: "badge-outline"
   defp badge_style_class(_), do: nil
 
+  @doc """
+  Renders a visually empty table cell with screen-reader-only text (WCAG).
+
+  Use when a table cell has no value so that:
+  - The cell appears empty (no dash, no "n/a").
+  - Screen readers still get a meaningful label (e.g. "No cycle", "No group assignment").
+
+  See CODE_GUIDELINES §8 (Empty table cells) and Design Guidelines §8.6.
+
+  ## Examples
+
+      <.empty_cell sr_text={gettext("No cycle")} />
+      <.empty_cell sr_text={gettext("No group assignment")} />
+      <.empty_cell sr_text={gettext("Not specified")} />
+  """
+  attr :sr_text, :string,
+    required: true,
+    doc: "Text read by screen readers when the cell is visually empty"
+
+  def empty_cell(assigns) do
+    ~H"""
+    <span class="sr-only">{@sr_text}</span>
+    """
+  end
+
+  @doc """
+  Renders content when value is present, otherwise an accessible empty cell.
+
+  Use in table cells for optional fields: when `value` is blank, only the
+  screen-reader text is shown (visually empty). Otherwise the inner block is rendered.
+
+  Blank check: `nil`, `false`, `[]`, `""`, whitespace-only string, or `%Ash.NotLoaded{}` count as empty.
+
+  See CODE_GUIDELINES §8 (Empty table cells) and Design Guidelines §8.6.
+
+  ## Examples
+
+      <.maybe_value value={member.membership_fee_type} empty_sr_text={gettext("No fee type")}>
+        {member.membership_fee_type.name}
+      </.maybe_value>
+      <.maybe_value value={member.groups} empty_sr_text={gettext("No group assignment")}>
+        <%= for g <- member.groups do %>
+          <.badge variant="primary" style="outline">{g.name}</.badge>
+        <% end %>
+      </.maybe_value>
+  """
+  attr :value, :any, doc: "Value to check; if blank, empty_cell is rendered"
+
+  attr :empty_sr_text, :string,
+    default: nil,
+    doc: "Screen-reader text when value is blank (default: gettext \"Not specified\")"
+
+  slot :inner_block, required: true
+
+  def maybe_value(assigns) do
+    empty_sr = assigns.empty_sr_text || gettext("Not specified")
+    assigns = assign(assigns, :empty_sr_text, empty_sr)
+    assigns = assign(assigns, :blank?, value_blank?(assigns.value))
+
+    ~H"""
+    <%= if @blank? do %>
+      <.empty_cell sr_text={@empty_sr_text} />
+    <% else %>
+      {render_slot(@inner_block)}
+    <% end %>
+    """
+  end
+
+  defp value_blank?(nil), do: true
+  defp value_blank?(false), do: true
+  defp value_blank?([]), do: true
+  defp value_blank?(%Ash.NotLoaded{}), do: true
+  defp value_blank?(v) when is_binary(v), do: String.trim(v) == ""
+  defp value_blank?(_), do: false
+
   @doc """
   Wraps content with a DaisyUI tooltip. Use for icon-only actions, truncated content,
   or status badges that need explanation (Design Guidelines §8.2).