fix: namespace rate limit buckets per endpoint, remove custom analytics

- Add `prefix` param to checkRateLimit/getRateLimitHeaders so each endpoint
  has its own bucket (previously all shared `admin_${ip}`, causing 429s when
  analytics/track incremented past n8n endpoints' lower limits)
- n8n/hardcover/currently-reading → prefix 'n8n-reading'
- n8n/status → prefix 'n8n-status'
- analytics/track → prefix 'analytics-track'
- Remove custom analytics system (AnalyticsProvider, lib/analytics,
  lib/useWebVitals, all /api/analytics/* routes) — was causing 500s in
  production due to missing PostgreSQL PageView table
- Remove analytics consent toggle from ConsentBanner/ConsentProvider

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/_ui/ProjectDetailClient.tsx

@@ -46,13 +46,7 @@ export default function ProjectDetailClient({
       setCanGoBack(true);
     }
     
-    try {
-      navigator.sendBeacon?.(
-        "/api/analytics/track",
-        new Blob([JSON.stringify({ type: "pageview", projectId: project.id.toString(), page: `/${locale}/projects/${project.slug}` })], { type: "application/json" }),
-      );
-    } catch {}
-  }, [project.id, project.slug, locale]);
+  }, []);
 
   const handleBack = (e: React.MouseEvent) => {
     e.preventDefault();