Set up Rails 8 application foundation

- Generate Rails 8.1 app with PostgreSQL and TailwindCSS
- Add docker-compose.yml (postgres:17) for local database
- Configure database.yml to connect to Dockerized Postgres via env vars
- Add Pages#home root route, application layout, and navbar partial

bin/bundler-audit

@@ -0,0 +1,6 @@
+#!/usr/bin/env ruby
+require_relative "../config/boot"
+require "bundler/audit/cli"
+
+ARGV.concat %w[ --config config/bundler-audit.yml ] if ARGV.empty? || ARGV.include?("check")
+Bundler::Audit::CLI.start