feat(admin): an all-accounts ledger section with filters and totals

There was no way to see the money as a whole: the ledger was only ever rendered
inside one account's card, so "what came in last month" meant exporting the
entire CSV and reading it elsewhere.

/_gm/ledger lists every operation, newest first, filtered by date range
(defaulting to the last 30 days), by wallet, by rail, by kind and by account.
Wallet and rail are deliberately separate axes because they answer different
questions — "what happened on VK" matches the funded segment or the benefit
origin, while "what came through YooKassa" matches the settling provider, and a
chip spend has no rail at all, so it drops out of that filter by construction.

Above the table sit the totals for everything the filter matches, not merely the
page on screen, which is the point of showing them. Money is listed per currency
because the rails settle in roubles, Votes and Stars and one sum across them
would mean nothing. Row amounts come from the operation snapshot, since the
ledger's own columns count chips rather than money.

Paging, the CSV export and a refund's way back are all built from the same
encoded filter, so none of them can quietly show a different slice than the
screen. The export moves here from the user card and gains the filter along with
money columns; it is capped, because an append-only ledger grows forever and an
unbounded export would eventually time out.

The refund action moves onto the funded rows here — an operator can now find a
payment by filter without knowing whose it is first — and returns to the same
filtered view. The destination travels with the form but is only honoured when
it is a console path, so a crafted form cannot turn it into an open redirect.

The user card keeps the account's standing rather than its history: balances,
benefits, the risk flag and a lifetime summary (money paid and refunded per
currency, chips credited and spent), plus a link into the ledger scoped to that
account. Operations are rendered in one place, with filters and paging, instead
of two.

Tests: the filter axes, paging that neither repeats nor drops a row, totals that
describe the range rather than the page, money recovered from a snapshot and
absent on a spend, and the console page, the export and the card hand-off. The
existing finance-panel test now asserts the summary and that the card no longer
re-renders the rows.

backend/internal/server/handlers_admin_refund.go

@@ -2,12 +2,9 @@ package server
 
 import (
 	"context"
-	"encoding/csv"
 	"errors"
 	"fmt"
-	"strconv"
 	"strings"
-	"time"
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/uuid"
@@ -27,7 +24,7 @@ func (s *Server) consoleRefund(c *gin.Context) {
 	if !ok {
 		return
 	}
-	back := "/_gm/users/" + id.String()
+	back := consoleReturnTo(c.PostForm("back"), "/_gm/users/"+id.String())
 	if s.payments == nil {
 		s.renderConsoleMessage(c, "Unavailable", "payments are not enabled", back)
 		return
@@ -69,6 +66,18 @@ func (s *Server) consoleRefund(c *gin.Context) {
 	s.renderConsoleMessage(c, "Refunded", msg, back)
 }
 
+// consoleReturnTo picks where the result page links back to: the caller's requested destination when
+// it is a console page, else the fallback. A refund can be started from the account card or from the
+// ledger (where the operator wants to land back on the same filtered slice), so the destination
+// travels with the form — but only ever as a console-relative path, never as an arbitrary URL a
+// crafted form could point elsewhere.
+func consoleReturnTo(requested, fallback string) string {
+	if strings.HasPrefix(requested, "/_gm/") && !strings.HasPrefix(requested, "/_gm//") {
+		return requested
+	}
+	return fallback
+}
+
 // refundOrder reverses a paid order, moving the money back through the rail's own refund API when
 // there is one. The provider call comes first and a failure aborts with nothing recorded: the ledger
 // must never claim a refund that did not happen. The reversal is then recorded under the provider's
@@ -93,27 +102,3 @@ func (s *Server) refundOrder(ctx context.Context, ref payments.OrderRef) (paymen
 	}
 	return s.payments.RefundOrderFullAs(ctx, ref.OrderID, providerYooKassa, refundID)
 }
-
-// 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()
-}