fix: 保证 Web observer 有界收尾

复用 stop-once 生命周期覆盖成功、失败、部分启动与异常兜底路径。\n\n将 YAML 派生的 maxRun/maxSamples 投影到 manifest 和 heartbeat，并补齐聚焦回归测试。

scripts/src/hwlab-node-web-observe-runner-runtime-source.ts

@@ -57,7 +57,17 @@ async function writeManifest(extra = {}) {
     navigation: { maxAttempts: navigationMaxAttempts, valuesRedacted: true },
     pageAuthority: { browser: "chromium", context: "shared-auth", pageMode: "dual-control-observer", controlPageId: pageId, observerPageId, continuityBreaksRecorded: true },
     pageProvenance: compactPageProvenance(currentPageProvenance),
-    sampling: { mode: "passive", sampleIntervalMs, screenshotIntervalMs, maxSamples, observerRefreshIntervalMs, observerInitiatedDefault: false, responseBodyReadDefault: false },
+    sampling: {
+      mode: "passive",
+      sampleIntervalMs,
+      screenshotIntervalMs,
+      maxSamples,
+      maxRunMs,
+      maxRunSeconds: maxRunMs > 0 ? Math.ceil(maxRunMs / 1000) : 0,
+      observerRefreshIntervalMs,
+      observerInitiatedDefault: false,
+      responseBodyReadDefault: false,
+    },
     alertThresholds,
     browserFreezePolicy,
     projectManagement,
@@ -84,6 +94,12 @@ async function writeHeartbeat(extra = {}) {
     currentUrl: currentPageUrl(),
     observerUrl: pageUrl(observerPage),
     observerRefreshIntervalMs,
+    observerLifecycle: {
+      maxSamples,
+      maxRunMs,
+      maxRunSeconds: maxRunMs > 0 ? Math.ceil(maxRunMs / 1000) : 0,
+      valuesRedacted: true,
+    },
     lastObserverRefreshAt: Number.isFinite(lastObserverRefreshAtMs) ? new Date(lastObserverRefreshAtMs).toISOString() : null,
     pageProvenance: compactPageProvenance(currentPageProvenance),
     sampleSeq,