refactor(terminology): 层级总结为主路径，synopsis 标记为旧式全局概要

- README: 明确 summaryState 为主总结体系，legacy synopsis 为兼容兜底
- prompt-profiles: synopsis 任务标签改为「小总结」
- schema/task-graph-stats/panel: synopsis 节点显示为「全局概要（旧）」
- index.js: fallback 状态文案改为「旧式全局概要生成/更新中」
- p0-regressions: 同步更新断言字符串

index.js

@@ -11041,7 +11041,7 @@ async function handleExtractionSuccess(
     typeof runHierarchicalSummaryPostProcess === "function"
       ? "层级总结"
       : typeof generateSynopsis === "function"
-        ? "概要生成"
+        ? "旧式全局概要生成"
         : "层级总结";
   const cloneMaintenanceSnapshot =
     typeof cloneGraphSnapshot === "function"
@@ -11163,9 +11163,9 @@ async function handleExtractionSuccess(
           ? getContext().chat
           : [];
       updateExtractionPostProcessStatus(
-        summaryStageLabel === "概要生成" ? "概要更新中" : "层级总结处理中",
-        summaryStageLabel === "概要生成"
-          ? `${extractionCount} 次提取，正在生成全局概要`
+        summaryStageLabel === "旧式全局概要生成" ? "旧式全局概要更新中" : "层级总结处理中",
+        summaryStageLabel === "旧式全局概要生成"
+          ? `${extractionCount} 次提取，正在生成旧式全局概要`
           : `${extractionCount} 次提取，正在检查小总结与折叠总结`,
       );
       const summaryResult = await runSummaryPostProcess({