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/catalog.go

@@ -18,6 +18,7 @@ const (
 	KindRuntimeContainerStartFailed = "runtime.container_start_failed"
 	KindRuntimeStartConfigInvalid = "runtime.start_config_invalid"
 	KindGameTurnReady = "game.turn.ready"
+	KindGamePaused = "game.paused"
 )
 
 // CatalogEntry describes the per-kind delivery policy: which channels
@@ -99,6 +100,9 @@ var catalog = map[string]CatalogEntry{
 	KindGameTurnReady: {
 		Channels: []string{ChannelPush},
 	},
+	KindGamePaused: {
+		Channels: []string{ChannelPush},
+	},
 }
 
 // LookupCatalog returns the per-kind policy and a boolean reporting
@@ -128,5 +132,6 @@ func SupportedKinds() []string {
 		KindRuntimeContainerStartFailed,
 		KindRuntimeStartConfigInvalid,
 		KindGameTurnReady,
+		KindGamePaused,
 	}
 }