test: self-contained local test account + urlencoded login

Add a dedicated, gitignored testrunner account auto-created by the suite
(make test-account, also invoked from global-setup) so `make test` no longer
needs the real account in .env. The target uses --admin-type both so the
account has admin.login for the gpx-manager specs. test-post.sh switches its
login POST to --data-urlencode to survive special chars in credentials.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Np4cMQLF77i664CAQXySzU

tests/global-setup.js

@@ -13,6 +13,14 @@ module.exports = async function globalSetup() {
         });
     }
 
+    // Local test-account defaults (mirror the Makefile) so direct `npx playwright
+    // test` runs are self-contained without needing GRAV_TEST_* in .env.
+    if (!process.env.GRAV_TEST_USER) process.env.GRAV_TEST_USER = 'testrunner';
+    if (!process.env.GRAV_TEST_PASS) process.env.GRAV_TEST_PASS = 'Testpass1234';
+
+    // Ensure the local test account exists (idempotent; never committed).
+    execSync('make test-account', { cwd: path.join(__dirname, '..'), stdio: 'inherit' });
+
     // Ensure demo content is loaded (italy-2026-demo trip + stories + GPX files)
     execSync('make demo-load', { cwd: path.join(__dirname, '..'), stdio: 'inherit' });
 };