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/src/domain/pageview-decision.spec.ts

@@ -0,0 +1,138 @@
+import { describe, expect, it } from "vitest";
+import {
+  decidePageview,
+  type IncomingPageviewRequest,
+} from "./pageview-decision";
+
+const humanRequest = (
+  overrides: Partial<IncomingPageviewRequest> = {},
+): IncomingPageviewRequest => ({
+  method: "GET",
+  pathname: "/",
+  search: "",
+  hostname: "mintel.me",
+  referrer: "",
+  language: "de-DE",
+  userAgent: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) Chrome/131.0.0.0",
+  clientIp: "84.117.2.55",
+  isRscNavigation: false,
+  isPrefetch: false,
+  ...overrides,
+});
+
+describe("decidePageview", () => {
+  it("tracks a document request for the homepage", () => {
+    const decision = decidePageview(humanRequest());
+    expect(decision).toEqual({
+      track: true,
+      facts: {
+        url: "/",
+        hostname: "mintel.me",
+        referrer: "",
+        language: "de-DE",
+        userAgent: humanRequest().userAgent,
+        clientIp: "84.117.2.55",
+      },
+    });
+  });
+
+  it("keeps the query string in the tracked url", () => {
+    const decision = decidePageview(
+      humanRequest({ pathname: "/imprint", search: "?from=footer" }),
+    );
+    expect(decision).toMatchObject({
+      track: true,
+      facts: { url: "/imprint?from=footer" },
+    });
+  });
+
+  it("tracks a blog-style slug that merely contains a file-like segment", () => {
+    const decision = decidePageview(
+      humanRequest({ pathname: "/blog/next.js-vs-remix" }),
+    );
+    expect(decision).toMatchObject({ track: true });
+  });
+
+  it("tracks a slug that merely starts like a metadata image route", () => {
+    const decision = decidePageview(
+      humanRequest({ pathname: "/notes/opengraph-image-deep-dive" }),
+    );
+    expect(decision).toMatchObject({ track: true });
+  });
+
+  it("tracks a client-side route change (RSC navigation without prefetch)", () => {
+    const decision = decidePageview(humanRequest({ isRscNavigation: true }));
+    expect(decision).toMatchObject({ track: true });
+  });
+
+  it("accepts the method in lower case", () => {
+    const decision = decidePageview(humanRequest({ method: "get" }));
+    expect(decision).toMatchObject({ track: true });
+  });
+
+  it.each([
+    ["a form submission", { method: "POST" }],
+    ["a head request", { method: "HEAD" }],
+    ["an options probe", { method: "OPTIONS" }],
+  ])("skips %s", (_label, overrides) => {
+    const decision = decidePageview(humanRequest(overrides));
+    expect(decision).toEqual({ track: false, reason: "non-get-method" });
+  });
+
+  it("skips a router prefetch", () => {
+    const decision = decidePageview(humanRequest({ isPrefetch: true }));
+    expect(decision).toEqual({ track: false, reason: "prefetch" });
+  });
+
+  it("skips a prefetch even when the agent is a bot", () => {
+    const decision = decidePageview(
+      humanRequest({ isPrefetch: true, userAgent: "curl/8.1.2" }),
+    );
+    expect(decision).toEqual({ track: false, reason: "prefetch" });
+  });
+
+  it.each([
+    ["a next build chunk", "/_next/static/chunks/main-abc123.js"],
+    ["a next image request", "/_next/image"],
+    ["a public image", "/images/portrait.webp"],
+    ["a jpeg photo", "/images/photo.jpg"],
+    ["a woff font", "/fonts/inter.woff"],
+    ["a font", "/fonts/inter.woff2"],
+    ["a feed document", "/rss.xml"],
+    ["the sitemap", "/sitemap.xml"],
+    ["the robots file", "/robots.txt"],
+    ["the web manifest", "/manifest.webmanifest"],
+    ["an open graph image route", "/opengraph-image"],
+    ["a twitter image route", "/twitter-image"],
+    ["a favicon", "/favicon.ico"],
+  ])("skips %s at %s", (_label, pathname) => {
+    const decision = decidePageview(humanRequest({ pathname }));
+    expect(decision).toEqual({ track: false, reason: "static-asset" });
+  });
+
+  it.each([
+    ["the analytics proxy", "/stats/api/send"],
+    ["the error relay", "/errors/api/relay"],
+    ["an api route", "/api/contact"],
+    ["the api health check", "/api/health"],
+    ["the health check", "/health"],
+    ["the gatekeeper", "/gatekeeper/api/verify"],
+    ["a well-known challenge", "/.well-known/acme-challenge/token"],
+  ])("skips %s at %s", (_label, pathname) => {
+    const decision = decidePageview(humanRequest({ pathname }));
+    expect(decision).toEqual({ track: false, reason: "infrastructure-path" });
+  });
+
+  it.each([
+    ["curl", "curl/8.1.2"],
+    ["wget", "Wget/1.21"],
+    ["python requests", "python-requests/2.31"],
+    ["go http", "Go-http-client/2.0"],
+    ["uptime kuma", "Uptime-Kuma/1.23.11"],
+    ["a crawler", "Googlebot/2.1 (+http://www.google.com/bot.html)"],
+    ["a link preview", "WhatsApp/2.23.20.0"],
+  ])("skips the %s user agent", (_label, userAgent) => {
+    const decision = decidePageview(humanRequest({ userAgent }));
+    expect(decision).toEqual({ track: false, reason: "bot-user-agent" });
+  });
+});