Mirror test layout, domcontentloaded waits, backup DB writes outside threads

tests/conftest.py

@@ -141,3 +141,16 @@ def page(browser):
 
 def pytest_sessionfinish(session, exitstatus):
     shutil.rmtree(TEST_DATA_DIR, ignore_errors=True)
+
+
+def login_admin(page, base_url):
+    page.goto(base_url + "/auth/login", wait_until="domcontentloaded")
+    page.fill("input[name=username]", ADMIN_USERNAME)
+    page.fill("input[name=password]", ADMIN_PASSWORD)
+    page.click("button[type=submit]")
+    page.wait_for_url("**/admin", wait_until="domcontentloaded")
+
+
+def assert_no_horizontal_overflow(page):
+    width, viewport = page.evaluate("[document.documentElement.scrollWidth, window.innerWidth]")
+    assert width <= viewport, f"horizontal overflow: {width} > {viewport}"