feat: billing — usage tracking per SQS operation in PostgreSQL

- New package app/billing: Init/RecordUsage/Close with auto-migrate
- Integration in actionHandler: record tenant_id, operation, msg_count, msg_bytes
- Helm chart: billing section in values.yaml, secret-billing.yaml, env vars in deployment
- Optional: billing disabled by default (BILLING_PG_HOST not set = no-op)
- Table: sqs_usage_records with index on (tenant_id, recorded_at)

app/router/router.go

@@ -13,6 +13,7 @@ import (
 
 	"shared-sqs/app/admin"
 	"shared-sqs/app/auth"
+	"shared-sqs/app/billing"
 	sqs "shared-sqs/app/gosqs"
 	"shared-sqs/app/interfaces"
 	"shared-sqs/app/tenant"
@@ -131,6 +132,16 @@ func actionHandler(w http.ResponseWriter, req *http.Request) {
 	if ok {
 		statusCode, responseBody := jsonFn(req)
 		encodeResponse(w, req, statusCode, responseBody)
+		// Billing: записываем каждую успешную SQS-операцию (async, no-op если billing выключен)
+		if statusCode < 400 {
+			if t, _ := req.Context().Value(auth.TenantContextKey).(*tenant.Tenant); t != nil {
+				msgBytes := req.ContentLength
+				if msgBytes < 0 {
+					msgBytes = 0
+				}
+				billing.RecordUsage(t.ID, action, 1, msgBytes)
+			}
+		}
 		return
 	}
 	log.Warnf("Bad Request - Action: %s", action)