Add RRULE humanizer and wire events into nodes#showerdgeist-revive-events

- app/models/concerns/rrule_humanizer.rb: new concern included into
  Event, renders recurring schedule as natural-language German or
  English from RRULE string; handles WEEKLY/MONTHLY, biweekly
  (INTERVAL=2), ordinal weekday positions (1TU, -1TH, -2WE),
  BYMONTH single-month exclusions (December pause convention);
  gracefully returns nil for COUNT/UNTIL/unrecognized shapes
- test/models/concerns/rrule_humanizer_test.rb: 15 tests covering
  all distinct RRULE shapes found in production data
- app/helpers/nodes_helper.rb: add event_schedule_text helper
  combining humanize_rrule with start_time formatting
- app/views/nodes/show.html.erb: add events row, conditionally
  rendered when node has associated events
- config/locales/de.yml, en.yml: add event_schedule_time,
  event_schedule_unrecognized, event_schedule_none keys

1 files changed, 16 insertions, 0 deletions

diff --git a/app/helpers/nodes_helper.rb b/app/helpers/nodes_helper.rb
index 4293628..329bcc5 100644
--- a/app/helpers/nodes_helper.rb
+++ b/app/helpers/nodes_helper.rb
@@ -43,4 +43,20 @@ module NodesHelper
       link_to('add event', new_event_path(:node_id => @node.id))
     ])
   end
+
+  def event_schedule_text(event)
+    if event.rrule.present?
+      recurrence = event.humanize_rrule(I18n.locale)
+      if recurrence
+        time = event.start_time&.strftime("%H:%M")
+        time ? "#{recurrence} #{t(:event_schedule_time, time: time)}" : recurrence
+      else
+        "#{event.rrule} (#{t(:event_schedule_unrecognized)})"
+      end
+    elsif event.start_time
+      I18n.l(event.start_time, format: :long)
+    else
+      t(:event_schedule_none)
+    end
+  end
 end