feat: M3 — 伏笔账本 + 节奏引擎 + 大纲（含并发记账 bugfix）

- 伏笔账本：纯函数状态机(OPEN/PARTIAL/CLOSED/OVERDUE) + ForeshadowLedger repo；验收后到期扫描(BackgroundTask 自建 session 置 OVERDUE)；登记/状态变更端点
- 节奏 + 三审齐：foreshadow-analyst + pace-checker 并入 LangGraph 并行审(REVIEW_SPECS)，collect 分列落 chapter_reviews(conflicts/foreshadow_sug/pace)，review SSE 加 foreshadow/pace 事件
- 大纲：outliner Agent 产 OutlineResult(含 foreshadow_windows)，POST /outline 逐章 upsert outline 表；GET /foreshadow?status= 看板
- 前端：伏笔四泳道看板(OVERDUE 琥珀) + 大纲编辑器(窗口徽标) + 节奏节拍图(▁▃▅) + 审稿页消费 foreshadow/pace SSE
- bugfix(T3.8)：并行三审共用请求 session 记账触发 'Session is already flushing' → foreshadow/pace 静默丢失；SqlAlchemyLedgerSink.record 改 add-only(靠端点/事务 commit)，加并发回归测试
- M3 E2E：真实 DB + mock 网关零 token 走通 埋设→进展→验收后扫描 OVERDUE→看板 + 大纲含窗口 + 三审齐 SSE/留痕；E2E 暴露并钉住上述 bug
- 门禁绿：mypy 111 / pytest 228(0 xfailed) / alembic 无漂移；前端 gen:api/lint/tsc/vitest 69/build

apps/web/components/review/ForeshadowSuggestions.tsx

@@ -0,0 +1,58 @@
+"use client";
+
+import type { ForeshadowSuggestion } from "@/lib/review/sse";
+
+interface ForeshadowSuggestionsProps {
+  suggestions: ForeshadowSuggestion[];
+  // 审项是否未完成（incomplete）。
+  incomplete: boolean;
+}
+
+// 伏笔建议区（UX §6.4 ②）：planted「新埋待确认」/ resolved「疑似回收」，只读建议。
+// 不静默写库（不变量#3）：仅展示，登记/回收经伏笔看板显式确认。
+export function ForeshadowSuggestions({
+  suggestions,
+  incomplete,
+}: ForeshadowSuggestionsProps) {
+  return (
+    <section className="mb-4">
+      <h2 className="text-xs font-semibold uppercase tracking-wide text-ink-soft">
+        伏笔 (foreshadow-analyst)
+      </h2>
+      {incomplete ? (
+        <p className="mt-1 text-xs text-overdue">◌ 未完成</p>
+      ) : suggestions.length === 0 ? (
+        <p className="mt-1 text-xs text-ink-soft">无伏笔建议。</p>
+      ) : (
+        <ul className="mt-2 space-y-2">
+          {suggestions.map((s, i) => (
+            <li
+              key={i}
+              className="rounded border border-line bg-panel p-2 text-xs"
+            >
+              <span
+                className={`mr-1 rounded px-1.5 py-0.5 ${
+                  s.kind === "resolved"
+                    ? "bg-pass/15 text-pass"
+                    : "bg-[var(--color-cinnabar-wash)] text-cinnabar"
+                }`}
+              >
+                {s.kind === "resolved" ? "⚑ 疑似回收" : "＋ 新埋待确认"}
+              </span>
+              {s.code ? (
+                <span className="font-mono text-ink-soft"> {s.code}</span>
+              ) : null}
+              <p className="mt-1 text-ink">{s.title}</p>
+              {s.where ? (
+                <span className="text-ink-soft">{s.where}</span>
+              ) : null}
+              {s.note ? (
+                <p className="mt-0.5 text-ink-soft">{s.note}</p>
+              ) : null}
+            </li>
+          ))}
+        </ul>
+      )}
+    </section>
+  );
+}