feat(analytics): add behavior and payment funnel tracking

src/app/_components/__tests__/tailwind-components.test.tsx

@@ -14,7 +14,12 @@ describe("shared Tailwind components", () => {
       <BackButton onClick={() => undefined} variant="ghost" />,
     );
     const darkHtml = renderToStaticMarkup(
-      <BackButton href="/splash" variant="dark" ariaLabel="Back to home" />,
+      <BackButton
+        href="/splash"
+        variant="dark"
+        ariaLabel="Back to home"
+        analyticsKey="chat.back_to_home"
+      />,
     );
 
     expect(linkHtml).toContain('href="/chat"');
@@ -27,6 +32,7 @@ describe("shared Tailwind components", () => {
     expect(actionHtml).toContain("hover:opacity-70");
     expect(darkHtml).toContain('href="/splash"');
     expect(darkHtml).toContain('aria-label="Back to home"');
+    expect(darkHtml).toContain('data-analytics-key="chat.back_to_home"');
     expect(darkHtml).toContain("bg-[rgba(13,11,20,0.7)]");
     expect(darkHtml).toContain("text-white");
   });