chore(labs): tidy the filter rail follow-ups

Drop a local-only ignore line, end the search placeholder with the
ellipsis character the other placeholders use, and put the
UrlFilterSyncOptions interface above the hook's doc comment so that
comment documents the hook.

src/components/labs/__tests__/lab-filter-rail.test.tsx

@@ -37,12 +37,12 @@ describe("<LabFilterRail>", () => {
     );
 
     expect(html).toContain('data-slot="lab-filter-rail"');
-    expect(html).toContain('placeholder="Search biomarkers..."');
+    expect(html).toContain('placeholder="Search biomarkers…"');
     expect(html).toContain('aria-keyshortcuts="/"');
     expect(html).toMatch(/<kbd[^>]*aria-hidden="true"[^>]*>\s*\/\s*<\/kbd>/);
 
     // The shared rail keeps search and all filter dimensions in one ordered row.
-    const searchIdx = html.indexOf('placeholder="Search biomarkers..."');
+    const searchIdx = html.indexOf('placeholder="Search biomarkers…"');
     const dateRangeIdx = html.indexOf("Last measured");
     const statusIdx = html.indexOf("Status");
     const categoryIdx = html.indexOf("Category");