feat: unify page titles

lib/mv_web/components/layouts.ex

@@ -13,6 +13,39 @@ defmodule MvWeb.Layouts do
 
   embed_templates "layouts/*"
 
+  @doc """
+  Builds the full browser tab title: "Mila", "Mila · Page", or "Mila · Page · Club".
+  Order is always: Mila · page title · club name.
+  Uses assigns[:club_name] and the short page label from assigns[:content_title] or
+  assigns[:page_title]. LiveViews should set content_title (same gettext as sidebar)
+  and then assign page_title to the result of this function so the client receives
+  the full title.
+  """
+  def page_title_string(assigns) do
+    club = assigns[:club_name]
+    page = assigns[:content_title] || assigns[:page_title]
+
+    parts =
+      [page, club]
+      |> Enum.filter(&(is_binary(&1) and String.trim(&1) != ""))
+
+    if parts == [] do
+      "Mila"
+    else
+      "Mila · " <> Enum.join(parts, " · ")
+    end
+  end
+
+  @doc """
+  Assigns content_title (short label for heading; same gettext as sidebar) and
+  page_title (full browser tab title). Call from LiveView mount after club_name
+  is set (e.g. from on_mount). Returns the socket.
+  """
+  def assign_page_title(socket, content_title) do
+    socket = assign(socket, :content_title, content_title)
+    assign(socket, :page_title, page_title_string(socket.assigns))
+  end
+
   @doc """
   Renders the public (unauthenticated) page layout: header with logo + "Mitgliederverwaltung" left,
   club name centered, language selector right; plus main content and flash group. Use for sign-in, join, and join-confirm pages so they