data: Add current_module_version SQL function

data/schema.sql

@@ -18,6 +18,24 @@ BEGIN
   RETURN NEW;
 END;
 $$ language 'plpgsql';
+
+
+CREATE OR REPLACE FUNCTION current_module_version(module_name TEXT)
+RETURNS INTEGER
+AS $$
+    SELECT 
+      to_version 
+    FROM version_history 
+    WHERE 
+      component = $1 
+    ORDER BY _timestamp DESC 
+    LIMIT 1;
+$$ LANGUAGE SQL;
+
+CREATE TABLE app_config(
+  appname TEXT PRIMARY KEY,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
 -- }}}
 
 -- App metadata {{{