feat(analytics): record pageviews server-side only

Umami never received data: the client-side path (browser beacon to
/stats/api/send) has been dead in production. Pageviews are now
classified and recorded entirely on the server in the request proxy;
no tracking script ships to the browser anymore.

- Pure domain decision (decidePageview) filters real page views from
  assets, infrastructure paths, prefetches and bot user agents
- Pure payload builder maps facts onto the Umami send contract as an
  unnamed event, with the client identity travelling in headers
- proxy.ts wires request facts into the domain and fires the send
  without delaying the response; configured via UMAMI_WEBSITE_ID and
  UMAMI_API_ENDPOINT
- Removes the dead client analytics stack (components, adapters,
  /stats proxy route) and its layout mount

apps/web/proxy.ts

@@ -0,0 +1,55 @@
+/**
+ * Server request shell. Reads the incoming request once, classifies it via
+ * the pure domain decision, and records a page view without touching the
+ * response. All analytics happen server-side; no tracking script ships to
+ * the browser.
+ */
+
+import { NextResponse, type NextRequest } from "next/server";
+
+import { recordPageviewToUmami } from "@/src/analytics/recordPageviewToUmami";
+import { decidePageview } from "@/src/domain/pageview-decision";
+
+const primaryLanguage = (acceptLanguage: string | null): string =>
+  acceptLanguage?.split(",")[0]?.split(";")[0]?.trim() ?? "";
+
+const firstForwardedIp = (forwardedFor: string | null): string =>
+  forwardedFor?.split(",")[0]?.trim() ?? "";
+
+const hostnameWithoutPort = (host: string): string => host.replace(/:\d+$/, "");
+
+const isPrefetchRequest = (request: NextRequest): boolean =>
+  request.headers.get("next-router-prefetch") === "1" ||
+  request.headers.get("purpose") === "prefetch" ||
+  request.headers.get("sec-purpose") === "prefetch";
+
+export default function proxy(request: NextRequest): NextResponse {
+  const decision = decidePageview({
+    method: request.method,
+    pathname: request.nextUrl.pathname,
+    search: request.nextUrl.search,
+    hostname: hostnameWithoutPort(
+      request.headers.get("x-forwarded-host") ??
+        request.headers.get("host") ??
+        "",
+    ),
+    referrer: request.headers.get("referer") ?? "",
+    language: primaryLanguage(request.headers.get("accept-language")),
+    userAgent: request.headers.get("user-agent") ?? "",
+    clientIp: firstForwardedIp(request.headers.get("x-forwarded-for")),
+    isRscNavigation: request.headers.get("rsc") === "1",
+    isPrefetch: isPrefetchRequest(request),
+  });
+
+  if (decision.track) {
+    recordPageviewToUmami(decision.facts);
+  }
+
+  return NextResponse.next();
+}
+
+export const config = {
+  matcher: [
+    "/((?!_next/static|_next/image|.*\\.(?:png|jpe?g|gif|svg|webp|avif|ico|css|mjs|cjs|js|map|txt|xml|json|webmanifest|woff2?|ttf|otf|mp4|webm|mov|pdf|zip)$).*)",
+  ],
+};