feat(GRO-1794): add booking funnel analytics events

- New analytics utility (src/lib/analytics.ts) with ANALYTICS_EVENTS constants
  and fireAnalyticsEvent() – thin wrapper over window.dispatchEvent, no-op safe
  Built for Plausible/GTM integration later.

- Public booking wizard (Book.tsx): fires step-transition events at each step
  (service → time → contact → submit) plus booking_confirmed on the dedicated
  confirmation page.

- Portal BookingFlow (Appointments.tsx): fires equivalent events for the
  portal booking flow. booking_confirmed fires via useEffect when the inline
  success state is shown.

- BookingErrorPage: fires booking_error on mount (no PII in payload).

Events include step name and flow type (public/portal) but contain no PII:
no names, emails, phone numbers, or pet names in any payload.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

src/__tests__/analytics.test.ts

@@ -0,0 +1,83 @@
+import { describe, it, expect } from "vitest";
+import { ANALYTICS_EVENTS, fireAnalyticsEvent } from "../lib/analytics";
+
+describe("analytics", () => {
+  describe("ANALYTICS_EVENTS constants", () => {
+    it("exports all required event names", () => {
+      expect(ANALYTICS_EVENTS.BOOKING_STEP_SERVICE).toBe("booking_step_service");
+      expect(ANALYTICS_EVENTS.BOOKING_STEP_TIME).toBe("booking_step_time");
+      expect(ANALYTICS_EVENTS.BOOKING_STEP_CONTACT).toBe("booking_step_contact");
+      expect(ANALYTICS_EVENTS.BOOKING_STEP_SUBMIT).toBe("booking_step_submit");
+      expect(ANALYTICS_EVENTS.BOOKING_CONFIRMED).toBe("booking_confirmed");
+      expect(ANALYTICS_EVENTS.BOOKING_ERROR).toBe("booking_error");
+    });
+
+    it("has no duplicate event names", () => {
+      const values = Object.values(ANALYTICS_EVENTS);
+      const unique = new Set(values);
+      expect(unique.size).toBe(values.length);
+    });
+  });
+
+  describe("fireAnalyticsEvent", () => {
+    it("dispatches a CustomEvent with the correct event name", () => {
+      const listener = vi.fn();
+      window.addEventListener(ANALYTICS_EVENTS.BOOKING_STEP_SERVICE, listener);
+      fireAnalyticsEvent(ANALYTICS_EVENTS.BOOKING_STEP_SERVICE, { step: "service", flow: "public" });
+      expect(listener).toHaveBeenCalledTimes(1);
+      const event = listener.mock.calls[0][0] as CustomEvent;
+      expect(event.type).toBe("booking_step_service");
+      expect(event.detail.step).toBe("service");
+      expect(event.detail.flow).toBe("public");
+      expect(event.detail.timestamp).toBeDefined();
+      window.removeEventListener(ANALYTICS_EVENTS.BOOKING_STEP_SERVICE, listener);
+    });
+
+    it("includes a timestamp in the event detail", () => {
+      const listener = vi.fn();
+      window.addEventListener(ANALYTICS_EVENTS.BOOKING_CONFIRMED, listener);
+      fireAnalyticsEvent(ANALYTICS_EVENTS.BOOKING_CONFIRMED, { step: "confirmed", flow: "public" });
+      const event = listener.mock.calls[0][0] as CustomEvent;
+      expect(event.detail.timestamp).toBeTruthy();
+      expect(new Date(event.detail.timestamp as string)).toBeInstanceOf(Date);
+      window.removeEventListener(ANALYTICS_EVENTS.BOOKING_CONFIRMED, listener);
+    });
+
+    it("does not throw when called with no payload", () => {
+      expect(() => {
+        fireAnalyticsEvent(ANALYTICS_EVENTS.BOOKING_ERROR, {});
+      }).not.toThrow();
+    });
+
+    it("does not throw when window.dispatchEvent throws", () => {
+      const original = window.dispatchEvent;
+      window.dispatchEvent = () => {
+        throw new Error("analytics blocked");
+      };
+      expect(() => {
+        fireAnalyticsEvent(ANALYTICS_EVENTS.BOOKING_STEP_SUBMIT, { step: "submit", flow: "public" });
+      }).not.toThrow();
+      window.dispatchEvent = original;
+    });
+
+    it("fires events for all event types", () => {
+      const events = Object.values(ANALYTICS_EVENTS);
+      for (const eventName of events) {
+        const listener = vi.fn();
+        window.addEventListener(eventName, listener);
+        fireAnalyticsEvent(eventName as typeof events[number], { step: "test", flow: "public" });
+        expect(listener).toHaveBeenCalledTimes(1);
+        window.removeEventListener(eventName, listener);
+      }
+    });
+
+    it("does not include PII in payload", () => {
+      // Payload only contains step, flow, and timestamp — no names, emails, or phones
+      const payload = { step: "contact", flow: "public" };
+      const keys = Object.keys(payload);
+      const piish = ["name", "email", "phone", "clientName", "clientEmail", "clientPhone", "petName"];
+      const hasPII = piish.some((k) => keys.includes(k));
+      expect(hasPII).toBe(false);
+    });
+  });
+});