feat(lobby): F8-04b hierarchical sidebar + paid-tier gate for create-game

Reshape the lobby UI from a single Overview into a two-level sidebar
(games · profile · DEV synthetic-reports) with four games sub-panels
(active-past · recruitment · invitations · private-games). Move the
`create new game` button into the private-games panel, merge the
applications section into recruitment cards as status chips, and add
DEV-only synthetic-report loader as a top-level screen.

Add a paid-tier gate at backend `lobby.game.create`: free callers get
`403 forbidden` before the lobby service is invoked. The UI hides the
private-games sub-panel + create button on free tier (DEV affordances
flag overrides). Update every integration test that creates a game to
use a new `testenv.PromoteToPaid` helper; add a new
`TestLobbyFlow_FreeUserCreateGameForbidden`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/internal/lobby/deps.go

@@ -9,14 +9,21 @@ import (
 
 // EntitlementProvider is the read-only view the lobby needs over the
 // user-domain entitlement snapshot. The canonical implementation is
-// `*user.Service` exposing `GetEntitlement(ctx, userID)`; tests substitute
-// a fake.
+// `*user.Service` exposing `GetEntitlementSnapshot(ctx, userID)`; tests
+// substitute a fake.
 //
-// `MaxRegisteredRaceNames` is the only field consumed by when
-// the caller attempts to register a `pending_registration` row the lobby
-// counts already-`registered` rows for that user against this limit.
+// `GetMaxRegisteredRaceNames` is consumed at race-name registration time
+// — when the caller attempts to register a `pending_registration` row the
+// lobby counts already-`registered` rows for that user against this limit.
+//
+// `IsPaid` is consumed by the user-facing private-game creation gate at
+// the HTTP handler level (`POST /api/v1/user/lobby/games`): free-tier
+// callers are rejected with `403 forbidden` before the lobby Service is
+// invoked. Admin-driven public-game creation
+// (`POST /api/v1/admin/games`) bypasses the gate.
 type EntitlementProvider interface {
 	GetMaxRegisteredRaceNames(ctx context.Context, userID uuid.UUID) (int32, error)
+	IsPaid(ctx context.Context, userID uuid.UUID) (bool, error)
 }
 
 // RuntimeGateway is the outbound surface the lobby uses to ask the runtime

backend/internal/lobby/lobby.go

@@ -20,6 +20,7 @@
 package lobby
 
 import (
+	"context"
 	"crypto/rand"
 	"encoding/hex"
 	"errors"
@@ -28,6 +29,7 @@ import (
 
 	"galaxy/backend/internal/config"
 
+	"github.com/google/uuid"
 	"github.com/jackc/pgx/v5/pgconn"
 	"go.uber.org/zap"
 )
@@ -207,6 +209,17 @@ func (s *Service) Config() config.LobbyConfig {
 	return s.deps.Config
 }
 
+// IsPaid reports whether userID currently sits on a paid tier. Thin
+// pass-through over EntitlementProvider used by the HTTP handler that
+// fronts user-driven private-game creation; admin-driven public-game
+// creation does not consult this gate.
+func (s *Service) IsPaid(ctx context.Context, userID uuid.UUID) (bool, error) {
+	if s == nil || s.deps.Entitlement == nil {
+		return false, fmt.Errorf("lobby: entitlement provider not configured")
+	}
+	return s.deps.Entitlement.IsPaid(ctx, userID)
+}
+
 // generateInviteCode produces an `inviteCodeBytes`-byte hex code used
 // for code-based invites. The function uses `crypto/rand`; a failure to
 // read entropy is propagated to the caller.

backend/internal/lobby/lobby_e2e_test.go

@@ -103,6 +103,10 @@ func (s stubEntitlement) GetMaxRegisteredRaceNames(_ context.Context, _ uuid.UUI
 	return s.max, nil
 }
 
+func (s stubEntitlement) IsPaid(_ context.Context, _ uuid.UUID) (bool, error) {
+	return true, nil
+}
+
 func newServiceForTest(t *testing.T, db *sql.DB, now func() time.Time, max int32) *lobby.Service {
 	t.Helper()
 	store := lobby.NewStore(db)

backend/internal/server/handlers_user_lobby_games.go

@@ -86,6 +86,15 @@ func (h *UserLobbyGamesHandlers) Create() gin.HandlerFunc {
 			return
 		}
 		ctx := c.Request.Context()
+		paid, err := h.svc.IsPaid(ctx, userID)
+		if err != nil {
+			respondLobbyError(c, h.logger, "user lobby games create", ctx, err)
+			return
+		}
+		if !paid {
+			httperr.Abort(c, http.StatusForbidden, httperr.CodeForbidden, "creating private games requires a paid subscription")
+			return
+		}
 		owner := userID
 		game, err := h.svc.CreateGame(ctx, lobby.CreateGameInput{
 			OwnerUserID: &owner,