chore: remove db $ instances

fix: add compute-schema file
fix: to_timestamp() psql usage

chore: rephrase expired session deletion

lib/compute-schema.js

@@ -0,0 +1,10 @@
+const { asyncLocalStorage, defaultStore } = require('./async-storage')
+
+const computeSchema = (req, res, next) => {
+  const store = defaultStore()
+  asyncLocalStorage.run(store, () => {
+    next()
+  })
+}
+
+module.exports = computeSchema