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/components/ConsentBanner.tsx

@@ -6,7 +6,7 @@ import { useTranslations } from "next-intl";
 
 export default function ConsentBanner() {
   const { consent, ready, setConsent } = useConsent();
-  const [draft, setDraft] = useState<ConsentState>({ analytics: false, chat: false });
+  const [draft, setDraft] = useState<ConsentState>({ chat: false });
   const [minimized, setMinimized] = useState(false);
   const t = useTranslations("consent");
 
@@ -19,7 +19,6 @@ export default function ConsentBanner() {
     title: t("title"),
     description: t("description"),
     essential: t("essential"),
-    analytics: t("analytics"),
     chat: t("chat"),
     alwaysOn: t("alwaysOn"),
     acceptAll: t("acceptAll"),
@@ -68,16 +67,6 @@ export default function ConsentBanner() {
             <div className="text-[11px] text-stone-500">{s.alwaysOn}</div>
           </div>
 
-          <label className="flex items-center justify-between gap-3 py-1">
-            <span className="text-sm font-semibold text-stone-800">{s.analytics}</span>
-            <input
-              type="checkbox"
-              checked={draft.analytics}
-              onChange={(e) => setDraft((p) => ({ ...p, analytics: e.target.checked }))}
-              className="w-4 h-4 accent-stone-900"
-            />
-          </label>
-
           <label className="flex items-center justify-between gap-3 py-1">
             <span className="text-sm font-semibold text-stone-800">{s.chat}</span>
             <input
@@ -91,7 +80,7 @@ export default function ConsentBanner() {
 
         <div className="mt-3 flex flex-col gap-2">
           <button
-            onClick={() => setConsent({ analytics: true, chat: true })}
+            onClick={() => setConsent({ chat: true })}
             className="px-4 py-2 rounded-xl bg-stone-900 text-stone-50 font-semibold hover:bg-stone-800 transition-colors"
           >
             {s.acceptAll}
@@ -103,7 +92,7 @@ export default function ConsentBanner() {
             {s.acceptSelected}
           </button>
           <button
-            onClick={() => setConsent({ analytics: false, chat: false })}
+            onClick={() => setConsent({ chat: false })}
             className="px-4 py-2 rounded-xl bg-transparent text-stone-600 font-semibold hover:text-stone-900 transition-colors"
           >
             {s.rejectAll}