style(web): move the row-count select into the card header

It was sitting in a strip below the heading with a "Show" label and a "newest
first" hint — three lines of chrome for one control. The select now lives at the
right end of the card's own header bar (`margin-left:auto` inside the flex h2),
compact and case-normal so it reads as a control and does not grow the bar.
Label and hint are gone; the header text names the card, the values speak for
themselves, and screen readers keep the `aria-label`.

tests/python/test_web_executions.py

@@ -385,7 +385,10 @@ def test_default_limit_is_ten(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -
 
     assert limits == [10]
     assert '<option value="10" selected>10</option>' in resp.text
-    assert "newest first" in resp.text
+    # The selector lives inside the card's header bar, not in a strip below it.
+    head = resp.text.split("</h2>", 1)[0]
+    assert "head-select" in head
+    assert "<label" not in resp.text
 
 
 def test_selector_offers_the_choices_and_marks_the_current_one(