Add backend unit/integration tests, Playwright e2e tests, README, cookie Secure fix

backend/tests/integration/setup/env.setup.ts

@@ -0,0 +1,11 @@
+// Runs before the test framework loads, so app.ts's Postgres pool (created
+// at import time) connects to the disposable test database instead of
+// whatever PGHOST/PGUSER happen to be set in the shell environment.
+process.env.NODE_ENV = 'test';
+process.env.PGHOST = process.env.TEST_PGHOST || 'localhost';
+process.env.PGPORT = process.env.TEST_PGPORT || '55432';
+process.env.PGUSER = process.env.TEST_PGUSER || 'redefined_test';
+process.env.PGPASSWORD = process.env.TEST_PGPASSWORD || 'redefined_test';
+process.env.PGDATABASE = process.env.TEST_PGDATABASE || 'redefined_test';
+process.env.DEMO_MODE = 'true';
+process.env.UPLOADS_DIR = '/tmp/redefined-test-uploads';