fix(admin): the gallery starts no thumbnail status read while it leaves

The gallery's startup thumbnail check runs one second after load. When that
second ended while the page was leaving (CI, WebKit: the workflow test
navigates from the gallery to the admin page), WebKit failed the new read
with "Fetch API cannot load ... due to access control checks." and
Playwright reported a page error.

Like the admin page (#290), the gallery now has a page lifetime that ends
on beforeunload and pagehide (and starts again on a back/forward restore).
The check starts no read once it has ended and passes it as the read's
signal. A page-clock workflow test that leaves before the second ends
failed on both events, in Chromium and WebKit, before this change.

tests/browser/shell-concept.spec.mjs

@@ -178,28 +178,27 @@ async function captureFooter(page,testInfo,name) {
 
 test.beforeEach(async({request})=>{await seedConcept(request);});
 
-// One test per route, size, theme and motion. All of them in one test per size and theme (12 page loads, 12 captures,
-// 36 hovers) steadily took 22 s median and up to 33 s on CI WebKit, past the 30 s budget with no step stalled; one
-// route in one motion is a sixth of that work under the same budget.
-for(const [route,breadcrumb] of ROUTES)for(const [width,height] of SIZES)for(const theme of THEMES)for(const motion of MOTIONS)test(`shell geometry, tokens and controls match the concept on ${route} ${width}x${height} ${theme} ${motion}`,async({page},testInfo)=>{
+for(const [width,height] of SIZES)for(const theme of THEMES)test(`shell geometry, tokens and controls match the concept ${width}x${height} ${theme}`,async({page},testInfo)=>{
     await page.setViewportSize({width,height});const result={};
-    await openConcept(page,route,theme,motion);await page.mouse.move(0,0);
-    const reference=await inventoryOf(page,'#main');
-    if(motion==='no-preference')await captureCanonicalState(page,testInfo,`concept-shell-${route}-${width}-${theme}`);
-    const referenceRings=FULL_HEADING.has(route)?await ringsOf(page,'#main'):null;
-    const referenceHovers=await hoversOf(page);
-    if(motion==='no-preference')await captureFooter(page,testInfo,`concept-footer-${route}-${width}-${theme}`);
-    await openProduction(page,route,theme,motion);await page.mouse.move(0,0);
-    const actual=await inventoryOf(page,'#workspace-main');
-    if(motion==='no-preference')await captureCanonicalState(page,testInfo,`production-shell-${route}-${width}-${theme}`);
-    const actualRings=FULL_HEADING.has(route)?await ringsOf(page,'#workspace-main'):null;
-    const actualHovers=await hoversOf(page);
-    if(motion==='no-preference')await captureFooter(page,testInfo,`production-footer-${route}-${width}-${theme}`);
-    result[`${motion} ${route}`]={reference,actual,diff:compare(route,reference,actual),referenceRings,actualRings,
-        referenceHovers,actualHovers};
-    const path=testInfo.outputPath(`shell-geometry-${route}-${motion}.json`);await writeFile(path,JSON.stringify(result,null,2));
-    await testInfo.attach(`shell-geometry-${route}-${motion}`,{path,contentType:'application/json'});
-    for(const [key,{reference,actual,diff,referenceRings,actualRings,referenceHovers,actualHovers}] of Object.entries(result)) {
+    for(const motion of MOTIONS)for(const [route,breadcrumb] of ROUTES) {
+        await openConcept(page,route,theme,motion);await page.mouse.move(0,0);
+        const reference=await inventoryOf(page,'#main');
+        if(motion==='no-preference')await captureCanonicalState(page,testInfo,`concept-shell-${route}-${width}-${theme}`);
+        const referenceRings=FULL_HEADING.has(route)?await ringsOf(page,'#main'):null;
+        const referenceHovers=await hoversOf(page);
+        if(motion==='no-preference')await captureFooter(page,testInfo,`concept-footer-${route}-${width}-${theme}`);
+        await openProduction(page,route,theme,motion);await page.mouse.move(0,0);
+        const actual=await inventoryOf(page,'#workspace-main');
+        if(motion==='no-preference')await captureCanonicalState(page,testInfo,`production-shell-${route}-${width}-${theme}`);
+        const actualRings=FULL_HEADING.has(route)?await ringsOf(page,'#workspace-main'):null;
+        const actualHovers=await hoversOf(page);
+        if(motion==='no-preference')await captureFooter(page,testInfo,`production-footer-${route}-${width}-${theme}`);
+        result[`${motion} ${route}`]={route,breadcrumb,reference,actual,diff:compare(route,reference,actual),referenceRings,actualRings,
+            referenceHovers,actualHovers};
+    }
+    const path=testInfo.outputPath('shell-geometry.json');await writeFile(path,JSON.stringify(result,null,2));
+    await testInfo.attach('shell-geometry',{path,contentType:'application/json'});
+    for(const [key,{route,breadcrumb,reference,actual,diff,referenceRings,actualRings,referenceHovers,actualHovers}] of Object.entries(result)) {
         // The concept itself is what this comparison assumes: its sample counts and its shell controls.
         expect.soft(reference.chrome.navs[0].rows.map(row=>[row.text,row.count?.text??null]),`${key} concept WORKSPACE rows`)
             .toEqual([['Images','24'],['Prompt library','6'],['Tags & categories','15'],['Inspect a file',null]]);

tests/browser/workspace-images.spec.mjs

@@ -787,12 +787,7 @@ test('density changes and resize preserve identity focus and selection', async (
     await page.getByRole('button',{name:'Grid',exact:true}).click();
     for (const [width,columns] of [[951,3],[950,3],[700,2],[390,2]]) {
         await page.setViewportSize({width,height:844});
-        // 700px and 390px both lay out two columns, so a card at the row start alone is also true of the previous
-        // width's cards before WebKit runs the first frame after the resize; wait for the row to fit the new grid.
-        await expect.poll(()=>page.locator('.image-grid').evaluate((grid,columns)=>{
-            const row=[...grid.querySelectorAll(':scope > article[data-image-key]')];
-            return row[columns].offsetLeft===0&&row[columns-1].getBoundingClientRect().right<=grid.getBoundingClientRect().right+1;
-        },columns)).toBe(true);
+        await expect.poll(()=>cards(page).nth(columns).evaluate(node=>node.offsetLeft)).toBe(0);
         await first.getByRole('button',{name:/^Open /}).focus();await page.keyboard.press('ArrowDown');
         await expect(cards(page).nth(columns).getByRole('button',{name:/^Open /})).toBeFocused();
         expect(await page.evaluate(()=>document.documentElement.scrollWidth-document.documentElement.clientWidth)).toBeLessThanOrEqual(1);