chore: import upstream snapshot with attribution

packages/db/connection-url.ts

@@ -0,0 +1,12 @@
+/**
+ * Resolve a connection URL for the active DB role, preferring the role-keyed
+ * variant (e.g. `DATABASE_URL_TRIGGER`) and falling back to the shared base.
+ * Lets each deploy point its surface at its own Postgres user + PgBouncer via
+ * env alone; unset keyed vars preserve the prior single-URL behavior.
+ */
+export function resolveDbUrl(
+  base: 'DATABASE_URL' | 'DATABASE_REPLICA_URL',
+  role: string
+): string | undefined {
+  return process.env[`${base}_${role.toUpperCase()}`] ?? process.env[base]
+}