A08: Pass errorPage on all pages with potential errors

Bug: Only index.astro passed errorPage={filterError}, missing:
- index.astro unavailable (503) — Dataset оставался на error page
- spots/[id].astro not found/unavailable — BreadcrumbList рендерился на 404
- records.astro unavailable (503) — no structuredData but should be explicit

Fix:
- index.astro: errorPage={filterError || unavailable}
- spots/[id].astro: errorPage={!spot || unavailable}
- records.astro: errorPage={unavailable}
- report.astro: не нужен (structuredData не передаётся)

Verification:
- Astro build: 0 errors
- Error pages (422, 503, 404) skip structuredData
- Normal pages include structuredData
- noindex still works for robots meta tag

apps/web/src/pages/spots/[id].astro

@@ -29,7 +29,7 @@ const breadcrumbs = spot ? { "@context": "https://schema.org", "@type": "Breadcr
   { "@type": "ListItem", position: 2, name: `${spot.waterbody} ${spot.x}:${spot.y}`, item: `https://rf4spotter.ru/spots/${spot.waterbody_slug}-${spot.x}x${spot.y}` },
 ] } : null;
 ---
-<Layout title={spot ? `Точка ${spot.x}:${spot.y}, ${spot.waterbody} — RF4 Spotter` : "Точка не найдена — RF4 Spotter"} description={spotDescription} noindex={!spot} structuredData={breadcrumbs}>
+<Layout title={spot ? `Точка ${spot.x}:${spot.y}, ${spot.waterbody} — RF4 Spotter` : "Точка не найдена — RF4 Spotter"} description={spotDescription} noindex={!spot} structuredData={breadcrumbs} errorPage={!spot || unavailable}>
   <a class="back" href="/">← Все активные точки</a>
   {unavailable || !spot ? <div class="state"><h1>Точка недоступна</h1><p>API не ответил или такой точки нет.</p></div> : <>
     <section class="spot-hero"><div><span class="eyebrow">{spot.waterbody}</span><h1>Точка {spot.x}:{spot.y}</h1><p>{spot.description}</p></div><CoordinateRadar x={spot.x} y={spot.y}/></section>