Merge dev into release merge branch

Resolve Backlogs sprint conflicts by porting the release assignability
changes onto the renamed Sprint model.

lookbook/docs/components/select-panel.md.erb

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+A `SelectPanel` is used when the user needs to select one or more items from a list. It combines a trigger button with a dropdown panel containing searchable, selectable items.
+The ability to search for items is what mainly separates this from the `ActionMenu` in our usage.
+
+For details on the component, please see the [Primer documentation](https://primer.style/product/components/select-panel/).
+
+## With footer button
+
+When selections need to be explicitly confirmed before taking effect, add a footer with an action button.
+The button should ideally be named "Apply".
+
+<%= embed Patterns::SelectPanelPreview, :footer_buttons, panels: %i[source] %>
+
+## Examples
+
+For detailed examples have a look at the other [preview examples](/lookbook/inspect/primer/alpha/select_panel/default) of the component.

lookbook/previews/patterns/select_panel_preview.rb

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+# frozen_string_literal: true
+
+#-- copyright
+# OpenProject is an open source project management software.
+# Copyright (C) the OpenProject GmbH
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License version 3.
+#
+# OpenProject is a fork of ChiliProject, which is a fork of Redmine. The copyright follows:
+# Copyright (C) 2006-2013 Jean-Philippe Lang
+# Copyright (C) 2010-2013 the ChiliProject Team
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# See COPYRIGHT and LICENSE files for more details.
+#++
+
+module Patterns
+  # @hidden
+  class SelectPanelPreview < ViewComponent::Preview
+    # @display min_height 400px
+    def footer_buttons
+      render_with_template
+    end
+  end
+end

lookbook/previews/patterns/select_panel_preview/footer_buttons.html.erb

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+<%=
+  render(
+    Primer::Alpha::SelectPanel.new(
+      select_variant: :multiple,
+      fetch_strategy: :local,
+      title: "Select roles",
+      open_on_load: true
+    )
+  ) do |panel|
+    panel.with_show_button(scheme: :secondary) do |button|
+      button.with_trailing_visual_icon(icon: :"triangle-down")
+      "3 roles selected"
+    end
+    panel.with_item(label: "Admin", active: true, item_id: "1")
+    panel.with_item(label: "Developer", active: true, item_id: "2")
+    panel.with_item(label: "Designer", active: true, item_id: "3")
+    panel.with_item(label: "Viewer", item_id: "4")
+    panel.with_item(label: "Copy project", item_id: "5")
+    panel.with_footer(show_divider: true) do
+      render(
+        Primer::Beta::Button.new(scheme: :primary)
+      ) { t(:button_apply) }
+    end
+  end
+%>