feat(admin): manual full-order refund + ledger CSV export

Closes the admin / reports / catalog work. Each fund row on the /_gm finance
panel gains a Refund action (payments.RefundOrderFull): a full-order refund the
operator records after refunding on the rail — a refund ledger row + a floor-0
chip revoke (never negative, D27), idempotent (a second refund reports
already-refunded). A ledger CSV export (/_gm/ledger.csv, payments.LedgerExport)
streams the whole append-only ledger for tax + reconciliation.

Tests: refund an order in full (chips revoked, a refund row), an idempotent
second refund, the CSV export shape; CSRF-guarded.

backend/internal/server/handlers_admin_console.go

@@ -60,6 +60,7 @@ func (s *Server) registerConsole(router *gin.Engine) {
 	gm.POST("/users/:id/remove-email", s.consoleRemoveEmail)
 	gm.POST("/users/:id/grant", s.consoleGrant)
 	gm.POST("/users/:id/grant-product", s.consoleGrantProduct)
+	gm.POST("/users/:id/refund", s.consoleRefund)
 	gm.POST("/users/:id/delete", s.consoleDeleteUser)
 	gm.GET("/reasons", s.consoleReasons)
 	gm.POST("/reasons", s.consoleCreateReason)
@@ -111,6 +112,7 @@ func (s *Server) registerConsole(router *gin.Engine) {
 		gm.POST("/catalog/:id", s.consoleUpdateProduct)
 		gm.POST("/catalog/:id/archive", s.consoleArchiveProduct)
 		gm.POST("/catalog/:id/delete", s.consoleDeleteProductAction)
+		gm.GET("/ledger.csv", s.consoleLedgerExport)
 	}
 }
 

backend/internal/server/handlers_admin_refund.go

@@ -0,0 +1,71 @@
+package server
+
+import (
+	"encoding/csv"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+)
+
+// consoleRefund refunds a paid order in full at the operator's request. The operator performs the
+// actual money refund on the rail (Robokassa cabinet / VK support / Telegram refundStarPayment);
+// this records it — a refund ledger row and a floor-0 chip revoke (never negative, D27). Idempotent.
+func (s *Server) consoleRefund(c *gin.Context) {
+	id, ok := s.consoleUUID(c, "/_gm/users")
+	if !ok {
+		return
+	}
+	back := "/_gm/users/" + id.String()
+	if s.payments == nil {
+		s.renderConsoleMessage(c, "Unavailable", "payments are not enabled", back)
+		return
+	}
+	orderID, err := uuid.Parse(strings.TrimSpace(c.PostForm("order_id")))
+	if err != nil {
+		s.renderConsoleMessage(c, "Refund failed", "no order to refund", back)
+		return
+	}
+	out, err := s.payments.RefundOrderFull(c.Request.Context(), orderID)
+	if err != nil {
+		s.renderConsoleMessage(c, "Refund failed", err.Error(), back)
+		return
+	}
+	if out.AlreadyRefunded {
+		s.renderConsoleMessage(c, "Already refunded", "this order was already refunded", back)
+		return
+	}
+	s.publishBannerChange(id)
+	msg := fmt.Sprintf("revoked %d chips", out.Revoked)
+	if out.Loss > 0 {
+		msg += fmt.Sprintf("; %d chips were already spent (recorded as a loss + abuse flag)", out.Loss)
+	}
+	s.renderConsoleMessage(c, "Refunded", msg, back)
+}
+
+// consoleLedgerExport streams the entire append-only ledger as a CSV attachment for tax reporting
+// and rail reconciliation. The snapshot column carries the raw purchase/refund JSON.
+func (s *Server) consoleLedgerExport(c *gin.Context) {
+	rows, err := s.payments.LedgerExport(c.Request.Context())
+	if err != nil {
+		s.consoleError(c, err)
+		return
+	}
+	c.Header("Content-Type", "text/csv; charset=utf-8")
+	c.Header("Content-Disposition", `attachment; filename="ledger.csv"`)
+	w := csv.NewWriter(c.Writer)
+	_ = w.Write([]string{
+		"created_at", "account_id", "kind", "source", "origin", "chips_delta",
+		"product_id", "order_id", "provider", "provider_payment_id", "snapshot",
+	})
+	for _, r := range rows {
+		_ = w.Write([]string{
+			r.CreatedAt.UTC().Format(time.RFC3339), r.AccountID, r.Kind, r.Source, r.Origin,
+			strconv.Itoa(r.ChipsDelta), r.ProductID, r.OrderID, r.Provider, r.ProviderPaymentID, r.Snapshot,
+		})
+	}
+	w.Flush()
+}