fix(026): e2e uses the neuroscape result-count testid (was OHBM-only)

The density e2e timed out 240s waiting for `result-count`, which only
exists on /ohbm2026/ (ResultList.svelte). NeuroScape's browse panel uses
`neuroscape-result-count`, text "461,316 matches · showing first 200" —
parse only the LEADING number so the "showing first N" suffix isn't
concatenated. Backdrop-count (plotly .data) + drag + clear paths were fine
(the run reached this helper after them).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: satra

site/src/tests/e2e/neuroscape_year_density.spec.ts

@@ -40,8 +40,13 @@ async function renderedBackdropCount(page: Page): Promise<number> {
 }
 
 async function resultCount(page: Page): Promise<number> {
-	const t = (await page.getByTestId('result-count').textContent())?.trim() ?? '0';
-	return Number.parseInt(t.replace(/[^0-9]/g, ''), 10) || 0;
+	// NeuroScape's count testid is `neuroscape-result-count` (the OHBM-only
+	// `result-count` does not exist here). Text is e.g.
+	// "461,316 matches · showing first 200" — parse only the LEADING number
+	// so the "showing first N" suffix isn't concatenated in.
+	const t = (await page.getByTestId('neuroscape-result-count').textContent())?.trim() ?? '';
+	const m = t.match(/[\d,]+/);
+	return m ? Number(m[0].replace(/,/g, '')) : 0;
 }
 
 /** Drag a slider handle to an absolute fraction of the track width. */