feat: complete commercial control plane, billing, auth, and model catalog

- add PostgreSQL control-plane persistence with Redis-degraded hot reload
- implement prepaid balance, usage ledger, Stripe top-up and reconciliation
- add registration, email verification, password reset, invitations and RBAC
- support TOTP, Passkey MFA, device sessions, quotas and rate limits
- add tenant billing profiles, audit logs and operational readiness checks
- build authenticated admin console, Quickstart, Playground and usage analytics
- add public model catalog with pricing, filtering and cost estimation
- support OpenAI Responses providers and provider health failover
- validate real upstream usage reporting and balance settlement

1 files changed, 34 insertions, 0 deletions

diff --git a/internal/controlplane/usage_analytics_test.go b/internal/controlplane/usage_analytics_test.go
new file mode 100644
index 0000000..2372be6
--- /dev/null
+++ b/internal/controlplane/usage_analytics_test.go
@@ -0,0 +1,34 @@
+package controlplane
+
+import "testing"
+
+func TestChargeChange(t *testing.T) {
+	tests := []struct {
+		name              string
+		current, previous int64
+		want              *float64
+	}{
+		{name: "no activity", current: 0, previous: 0, want: nil},
+		{name: "new spend has no finite percentage", current: 25, previous: 0, want: nil},
+		{name: "increase", current: 125, previous: 25, want: floatPointer(400)},
+		{name: "decrease", current: 25, previous: 100, want: floatPointer(-75)},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got := chargeChange(test.current, test.previous)
+			if test.want == nil {
+				if got != nil {
+					t.Fatalf("chargeChange() = %v, want nil", *got)
+				}
+				return
+			}
+			if got == nil || *got != *test.want {
+				t.Fatalf("chargeChange() = %v, want %v", got, *test.want)
+			}
+		})
+	}
+}
+
+func floatPointer(value float64) *float64 {
+	return &value
+}