fix(formula): add sha256 hash for postgresai tarball

Author: claude

Formula/postgresai.rb

@@ -5,7 +5,7 @@ class Postgresai < Formula
   desc "postgres_ai CLI (Node.js)"
   homepage "https://gitlab.com/postgres-ai/postgres_ai"
   url "https://registry.npmjs.org/postgresai/-/postgresai-0.14.0-beta.3.tgz"
-  sha256 "" # Will be calculated after publishing to npm
+  sha256 "8de506a7384578b95aa6bfb4e0142c483298478e1b7d6d49c9ed5b2e9bb935c9"
   license "Apache-2.0"
 
   depends_on "node"