Implement Monlet MVP stack and UI updates

deploy/showcase/seed_discarded.sql

@@ -0,0 +1,16 @@
+-- Seed one outbox row with an unknown notifier name so the worker marks it 'discarded'.
+-- Attached to any existing incident; if none exists yet the script is a no-op.
+INSERT INTO notification_outbox
+    (id, incident_id, notifier, event_type, state, attempts, next_attempt_at, payload)
+SELECT
+    gen_random_uuid(),
+    i.id,
+    'showcase-unknown',
+    'firing',
+    'pending',
+    0,
+    now(),
+    '{"showcase":"discarded"}'::jsonb
+FROM incidents i
+ORDER BY i.opened_at DESC
+LIMIT 1;