ui/phase-25: backend turn-cutoff guard + auto-pause + UI sync protocol

Backend now owns the turn-cutoff and pause guards the order tab
relies on: the scheduler flips runtime_status between
generation_in_progress and running around every engine tick, a
failed tick auto-pauses the game through OnRuntimeSnapshot, and a
new game.paused notification kind fans out alongside
game.turn.ready. The user-games handlers reject submits with
HTTP 409 turn_already_closed or game_paused depending on the
runtime state.

UI delegates auto-sync to a new OrderQueue: offline detection,
single retry on reconnect, conflict / paused classification.
OrderDraftStore surfaces conflictBanner / pausedBanner runes,
clears them on local mutation or on a game.turn.ready push via
resetForNewTurn. The order tab renders the matching banners and
the new conflict per-row badge; i18n bundles cover en + ru.

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

backend/internal/notification/events_test.go

@@ -20,8 +20,14 @@ import (
 // other consumer reads the payload — adopting the FB encoder would
 // require a new TS notification stub set and the regen tooling for
 // `pkg/schema/fbs/notification.fbs` without buying anything.
+//
+// `game.paused` (Phase 25) follows the same JSON-friendly contract:
+// payload is `{game_id, turn, reason}` consumed by the same in-game
+// shell layout, so there is no value in dragging a FB schema in for
+// one consumer.
 var jsonFriendlyKinds = map[string]bool{
 	KindGameTurnReady: true,
+	KindGamePaused:    true,
 }
 
 // TestBuildClientPushEventCoversCatalog asserts that every catalog kind
@@ -77,6 +83,11 @@ func TestBuildClientPushEventCoversCatalog(t *testing.T) {
 			"game_id": gameID.String(),
 			"turn":    int32(7),
 		}},
+		{"game paused", KindGamePaused, map[string]any{
+			"game_id": gameID.String(),
+			"turn":    int32(7),
+			"reason":  "generation_failed",
+		}},
 	}
 
 	seenKinds := map[string]bool{}