feat(admin): manual account blocking (suspensions)

Operator-driven hard block, the counterpart to the soft high-rate flag: permanent or until a date, with an optional reason chosen from an editable en+ru picklist (snapshotted onto the block). A block forfeits the player's active games (opponent wins, as a resignation) and cancels their open matchmaking games. A backend gate refuses a blocked account on every /api/v1/user/* route except the block-status probe with 403 account_blocked, which threads through the gateway as the Execute result_code; the UI surfaces it as a terminal blocked screen and stops all push/poll. Temporary blocks self-expire; the operator can unblock at any time (lost games stay lost). Sessions are not revoked, so the blocked client can still reach the exempt block-status endpoint.

Backend: migration 00003 (account_suspensions + suspension_reasons) + jet regen; account suspension store; game.ForfeitAllForAccount; requireNotSuspended gate + block-status endpoint; admin console block/unblock + Reasons CRUD. Wire: fbs BlockStatus + account.block_status gateway op. UI: blocked screen, app state, transport/codec, i18n. Docs: ARCHITECTURE, FUNCTIONAL(+ru), PRERELEASE (AB).

gateway/internal/transcode/transcode_block_test.go

@@ -0,0 +1,64 @@
+package transcode_test
+
+import (
+	"context"
+	"net/http"
+	"testing"
+
+	"scrabble/gateway/internal/transcode"
+	fb "scrabble/pkg/fbs/scrabblefb"
+)
+
+// TestBlockStatusRoundTrip checks the account.block_status op forwards to the backend block-status
+// endpoint and encodes its JSON into the BlockStatus FlatBuffer.
+func TestBlockStatusRoundTrip(t *testing.T) {
+	backend, cleanup := fakeBackend(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/api/v1/user/block-status" {
+			t.Errorf("path = %q, want /api/v1/user/block-status", r.URL.Path)
+		}
+		_, _ = w.Write([]byte(`{"blocked":true,"permanent":false,"until":"2026-07-01T12:00:00Z","reason":"Спам"}`))
+	})
+	defer cleanup()
+
+	reg := transcode.NewRegistry(backend, nil)
+	op, ok := reg.Lookup(transcode.MsgBlockStatus)
+	if !ok {
+		t.Fatal("account.block_status not registered")
+	}
+	payload, err := op.Handler(context.Background(), transcode.Request{UserID: "u-1"})
+	if err != nil {
+		t.Fatalf("handler: %v", err)
+	}
+	bs := fb.GetRootAsBlockStatus(payload, 0)
+	if !bs.Blocked() || bs.Permanent() {
+		t.Fatalf("blocked=%v permanent=%v, want true/false", bs.Blocked(), bs.Permanent())
+	}
+	if string(bs.Until()) != "2026-07-01T12:00:00Z" {
+		t.Errorf("until = %q, want the forwarded instant", bs.Until())
+	}
+	if string(bs.Reason()) != "Спам" {
+		t.Errorf("reason = %q, want Спам", bs.Reason())
+	}
+}
+
+// TestBlockedBackendSurfacesDomainCode checks that a backend 403 with code account_blocked (the
+// suspension gate) surfaces as a domain code, which the Execute layer turns into the envelope
+// result_code the UI keys off.
+func TestBlockedBackendSurfacesDomainCode(t *testing.T) {
+	backend, cleanup := fakeBackend(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusForbidden)
+		_, _ = w.Write([]byte(`{"error":{"code":"account_blocked","message":"account is blocked"}}`))
+	})
+	defer cleanup()
+
+	reg := transcode.NewRegistry(backend, nil)
+	op, _ := reg.Lookup(transcode.MsgProfileGet) // any gated op hits the same gate
+	_, err := op.Handler(context.Background(), transcode.Request{UserID: "u-1"})
+	if err == nil {
+		t.Fatal("expected an error from a blocked backend response")
+	}
+	code, ok := transcode.DomainCode(err)
+	if !ok || code != "account_blocked" {
+		t.Fatalf("DomainCode = (%q, %v), want (account_blocked, true)", code, ok)
+	}
+}