Fix live camera pose loading and relay buffer

tests/e2e/helpers/mockApp.ts

@@ -50,6 +50,7 @@ type MockMediaSession = {
   uploadedSegments: number;
   uploadedBytes: number;
   durationMs: number;
+  relayBufferSeconds?: number;
   previewUpdatedAt?: string;
   streamConnected: boolean;
   viewerCount?: number;
@@ -288,6 +289,7 @@ function buildMediaSession(
     uploadedSegments: purpose === "relay" ? 1 : 0,
     uploadedBytes: purpose === "relay" ? 1_280_000 : 0,
     durationMs: purpose === "relay" ? 60_000 : 0,
+    relayBufferSeconds: purpose === "relay" ? 120 : undefined,
     previewUpdatedAt: purpose === "relay" ? nowIso() : undefined,
     streamConnected: true,
     playback: {
@@ -858,6 +860,7 @@ export async function installAppMocks(
               title: "其他设备实时分析",
               sessionMode: "practice",
               qualityPreset: "balanced",
+              relayBufferSeconds: 120,
               facingMode: "environment",
               deviceKind: "mobile",
               avatarEnabled: true,