feat(settings): default the site tagline

backend/src/migrations/010_default_tagline.sql

@@ -0,0 +1,11 @@
+-- ===================================
+-- Migration 010: Default site tagline
+-- ===================================
+-- Give the tagline a default, applied where it was still empty. Clearing it in
+-- the admin settings afterwards still hides it.
+
+UPDATE system_settings
+SET
+  default_value = 'The Flash arcade that never closed',
+  value = CASE WHEN value = '' THEN 'The Flash arcade that never closed' ELSE value END
+WHERE key = 'app.tagline';

docs/10-features/09-system-settings.md

@@ -69,7 +69,8 @@ CREATE TABLE system_settings (
 #### App Tab
 
 - **Site Name** - Customize application name
-- **Tagline** - Optional line shown under the site name in the portal header
+- **Tagline** - Line shown under the site name in the portal header (default:
+  "The Flash arcade that never closed"; clear it to hide it)
 - **Maintenance Mode** - Enable/disable maintenance mode
 - **Default Theme** - Set default theme (light, dark, system)
 - **Default Primary Color** - Set default color scheme