add favicon and manifest links

sqlpage/sqlpage/internal/theme.sql

@@ -4,3 +4,8 @@ SELECT 'shell' AS component
 , '/grocery/'||lower($title)||'.sql' AS link
 , '/grocery/favicon.svg' AS image
 ;
+
+SELECT 'text' AS component
+, '<link rel="favicon" href="/grocery/favicon.svg"/>
+<link rel="manifest" href="/grocery/manifest.json"/>' AS html
+;