Add UNLOGGED tables rake task for optional test performance

Adds db:test:unlogged task that converts all PostgreSQL tables to
UNLOGGED mode. UNLOGGED tables skip WAL logging, which can make
writes faster during test setup.

Benchmarks on this codebase showed minimal impact (~1%):
- Model specs: 13.7s (LOGGED) vs 13.8s (UNLOGGED)
- Full suite: 87s (LOGGED) vs 86s (UNLOGGED)

The benefit depends on your test suite characteristics:
- More useful if you have many feature specs with heavy database writes
- Less useful if most tests use transactional fixtures

Auto-runs after db:test:prepare when in test environment.
Can be removed if it causes issues or doesn't help your workload.

Author: mroderick

lib/tasks/test_unlogged.rake

@@ -0,0 +1,27 @@
+namespace :db do
+  namespace :test do
+    desc "Convert all tables to UNLOGGED for faster test performance"
+    task unlogged: :environment do
+      raise "This task only works in test environment" unless Rails.env.test?
+
+      tables = ActiveRecord::Base.connection.tables
+      converted = 0
+      tables.each do |table|
+        next if table == "schema_migrations" || table == "ar_internal_metadata"
+        result = ActiveRecord::Base.connection.execute(
+          "SELECT relpersistence FROM pg_class WHERE relname = '#{table}'"
+        )
+        if result.first && result.first["relpersistence"] != "u"
+          ActiveRecord::Base.connection.execute("ALTER TABLE #{table} SET UNLOGGED")
+          converted += 1
+        end
+      end
+      puts "Converted #{converted} tables to UNLOGGED" if converted > 0
+    end
+  end
+end
+
+# Auto-run after db:test:prepare
+Rake::Task["db:test:prepare"].enhance do
+  Rake::Task["db:test:unlogged"].invoke if Rails.env.test?
+end