fix(sidebar): Omdøb og Slet lå oven i hinanden i et gruppehoved

The "+" beside "Projekter" is a 20px square icon button, and the rule that
makes it one was written as `.group-head > button`. A group's heading is
also a `.group-head`, and it has two buttons in it that are words rather
than icons — so Omdøb and Slet were each squeezed into a 20px box, where
they overflowed and were drawn on top of each other.

They still worked. Every assertion in the smoke test clicks by accessible
name, which is unaffected by a button being the wrong size, so the whole
suite passed on a heading that read "0 Om…Slet". It took a screenshot from
somebody actually using it.

The selector now asks for the class instead of for "a button in a
heading", so the next text button added there is safe by default rather
than by remembering.

And the smoke test measures the row: each button must start at or after
the previous one's right edge. A layout assertion is unusual here on
purpose — the rest of the file deliberately tests behaviour — but this is
a failure mode behaviour cannot see.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

web/e2e/smoke.spec.js

@@ -257,6 +257,25 @@ test('en projektgruppe kan foldes, fyldes og slettes uden at tage projekterne me
 	await expect(heading).toBeVisible();
 	await expect(sidebar.getByText('Træk et projekt herop')).toBeVisible();
 
+	// The words in the heading must not sit on top of each other.
+	//
+	// Everything else here clicks by accessible name, which is exactly why this
+	// needs saying out loud: "Omdøb" and "Slet" once got the 20px square meant for
+	// the "+" icon beside "Projekter", overflowed it, and were drawn overlapping.
+	// Both buttons still worked, so every assertion in this file passed.
+	const boxes = await sidebar.locator('.folder-head').evaluate((el) =>
+		[...el.querySelectorAll('button')].map((b) => {
+			const r = b.getBoundingClientRect();
+			return { text: b.textContent.trim(), left: r.left, right: r.right };
+		})
+	);
+	for (let i = 1; i < boxes.length; i++) {
+		expect(
+			boxes[i].left,
+			`"${boxes[i - 1].text}" og "${boxes[i].text}" overlapper i gruppehovedet`
+		).toBeGreaterThanOrEqual(boxes[i - 1].right);
+	}
+
 	// Dragged in, then dragged back out onto "Projekter" — which is the reason
 	// that heading is a drop target at all: with every project filed away there
 	// would otherwise be no loose row left to aim at.