fix: 应用 xhigh 代码评审的跨端修复

来自 xhigh code review 的正确性/健壮性修复，覆盖全部五端：
- server：鉴权 fail-closed、计量交叉校验与配额扣穿处理、WS 网关并发与关闭顺序、
  billing 行锁、redis Lua 过期与设备槽刷新、config 解析
- desktop：会话 epoch 防串话、WS 重连与 401 处理、api 客户端复用、统一 usePoll 轮询
- android：握手时序、请求头封装、账户状态派生、按需重组
- ios：finalize 宽限、串行采集、错误文案服务端优先、删除死代码 CommitController

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/internal/gateway/gateway_test.go

@@ -1,7 +1,6 @@
 package gateway
 
 import (
-	"context"
 	"encoding/json"
 	"net/http/httptest"
 	"strings"
@@ -155,35 +154,45 @@ func TestQuotaExceededOnStart(t *testing.T) {
 	}
 }
 
-// mrConsumeAll 把 u1 的当日试用直接耗尽（经 quota 通道，保证键一致）。
+// mrConsumeAll 把 u1 的当日试用耗尽（经 quota 通道，保证键一致）。
+// 单会话被截断在略低于 180s 处（截断帧不再计费，16A），故一会话不足以扣满 180s 试用；
+// 此处循环开会话推音频，直到某个 usage 帧报告 TrialRemaining<=0 为止。
 func mrConsumeAll(t *testing.T, srv *httptest.Server, db *gorm.DB) {
 	t.Helper()
-	conn := dial(t, srv)
-	start, _ := json.Marshal(protocol.ClientMsg{Type: "start", SessionID: "s0", SampleRate: 16000})
-	_ = conn.WriteMessage(websocket.TextMessage, start)
 	frame := make([]byte, protocol.FrameBytes)
-	// 180s 音频 = 1800 帧
-	for i := 0; i < protocol.TrialDailySeconds*10; i++ {
-		if err := conn.WriteMessage(websocket.BinaryMessage, frame); err != nil {
-			t.Fatal(err)
+	deadline := time.Now().Add(15 * time.Second)
+	for sess := 0; sess < 5 && time.Now().Before(deadline); sess++ {
+		conn := dial(t, srv)
+		sid := "s0_" + string(rune('a'+sess))
+		start, _ := json.Marshal(protocol.ClientMsg{Type: "start", SessionID: sid, SampleRate: 16000})
+		_ = conn.WriteMessage(websocket.TextMessage, start)
+		// 推 180s 音频（1800 帧）→ 会话在临界处截断
+		for i := 0; i < protocol.TrialDailySeconds*10; i++ {
+			if err := conn.WriteMessage(websocket.BinaryMessage, frame); err != nil {
+				break
+			}
+		}
+		stop, _ := json.Marshal(protocol.ClientMsg{Type: "stop", SessionID: sid})
+		_ = conn.WriteMessage(websocket.TextMessage, stop)
+
+		exhausted := false
+		for time.Now().Before(deadline) {
+			_ = conn.SetReadDeadline(time.Now().Add(2 * time.Second))
+			var msg protocol.ServerMsg
+			if err := conn.ReadJSON(&msg); err != nil {
+				break
+			}
+			if msg.Type == protocol.MsgUsage && msg.TrialRemaining <= 0 {
+				exhausted = true
+				break
+			}
+		}
+		conn.Close()
+		if exhausted {
+			return
 		}
 	}
-	stop, _ := json.Marshal(protocol.ClientMsg{Type: "stop", SessionID: "s0"})
-	_ = conn.WriteMessage(websocket.TextMessage, stop)
-	// 读到连接收尾的 usage 帧为止
-	deadline := time.Now().Add(5 * time.Second)
-	for time.Now().Before(deadline) {
-		_ = conn.SetReadDeadline(time.Now().Add(2 * time.Second))
-		var msg protocol.ServerMsg
-		if err := conn.ReadJSON(&msg); err != nil {
-			break
-		}
-		if msg.Type == protocol.MsgUsage && msg.SessionSeconds >= protocol.TrialDailySeconds {
-			break
-		}
-	}
-	conn.Close()
-	_ = context.Background()
+	t.Fatal("failed to exhaust trial via repeated sessions")
 }
 
 func TestSessionLimitTruncates(t *testing.T) {