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

Makefile

@@ -36,13 +36,23 @@ $(foreach t,$(REMOTE_TARGETS),$(foreach e,$(ENVS),$(eval $(call make-env-target,
 
 # ── Tests ─────────────────────────────────────────────────────────────────────
 
+# Local test account — auto-created, never committed (see user/.gitignore).
+# Keep the password free of shell/Make/URL-special chars so every consumer agrees.
+GRAV_TEST_USER ?= testrunner
+GRAV_TEST_PASS ?= Testpass1234
+
+test-account:
+	@docker exec intotheeast_grav sh -c 'test -f /var/www/html/user/accounts/$(GRAV_TEST_USER).yaml \
+		|| php bin/plugin login new-user -u $(GRAV_TEST_USER) -p "$(GRAV_TEST_PASS)" \
+		   -e $(GRAV_TEST_USER)@example.test -N "Test Runner" -P b --admin-type both -s enabled -n'
+
 test-config:
 	@bash scripts/test-form-config.sh
 
-test-post:
+test-post: test-account
 	@bash scripts/test-post.sh
 
-test-ui:
+test-ui: test-account
 	@npx playwright test
 
 test: test-config test-post test-ui