feat: 完成 C 群組 — 記憶子系統

- WorkingMemoryService：session 對話上下文緩衝，token 溢位時優先裁切最舊的低情緒段落
- JobQueue 抽象層（now/schedule(at)/every(cron)）與 InProcessJobQueue 實作（node-cron），
  R-6 會換成 BullMQ 但呼叫端介面不變
- MemoryConsolidationService：睡眠固化，只有高情緒或重複提及的內容才寫入 EpisodicMemory
- ForgettingSweepService：低情緒且長期未提取的記憶逐次降權、weight 過低後刪除，
  已掛上每小時一次的 JobQueue.every 排程
- KeywordMemoryRetriever：關鍵字＋時間近因＋情緒權重排序，提取命中即更新提取次數／時間
- apps/api 新增 /memory/* 端點作為引擎驗證介面（H 群組會決定併入正式對話管線後的去留）
- scripts/smoke/C.mjs：端到端驗證溢位裁切、只寫工作記憶、固化篩選、檢索排序、
  提取即改寫、schedule(at) 準時觸發、遺忘衰減與刪除

npm run restart && npm run smoke -- C 皆通過（C-V），A/B 群組冒煙測試無回歸。

apps/api/src/memory/memory-consolidation.service.ts

@@ -0,0 +1,51 @@
+import { Injectable } from "@nestjs/common";
+import { PrismaService } from "../prisma/prisma.service.js";
+import { WorkingMemoryService } from "./working-memory.service.js";
+import { HIGH_EMOTION_THRESHOLD } from "./constants.js";
+
+function normalize(content: string): string {
+  return content.trim().toLowerCase();
+}
+
+// C-4 睡眠固化：對話中只累積在工作記憶，session 結束時才批次萃取寫入長期記憶。
+@Injectable()
+export class MemoryConsolidationService {
+  constructor(
+    private readonly prisma: PrismaService,
+    private readonly workingMemory: WorkingMemoryService,
+  ) {}
+
+  async consolidate(characterId: string, sessionId: string): Promise<void> {
+    const entries = this.workingMemory.getContext(sessionId);
+
+    const contentCounts = new Map<string, number>();
+    for (const entry of entries) {
+      const key = normalize(entry.content);
+      contentCounts.set(key, (contentCounts.get(key) ?? 0) + 1);
+    }
+
+    for (const entry of entries) {
+      const emotionIntensity = entry.emotionIntensity ?? 0;
+      const isHighEmotion = emotionIntensity >= HIGH_EMOTION_THRESHOLD;
+      const isRepeated = (contentCounts.get(normalize(entry.content)) ?? 0) > 1;
+
+      if (!isHighEmotion && !isRepeated) {
+        continue;
+      }
+
+      await this.prisma.client.episodicMemory.create({
+        data: {
+          characterId,
+          content: entry.content,
+          occurredAt: entry.timestamp,
+          emotionTag: entry.emotionTag ?? "CALM",
+          emotionIntensity,
+          source: "INTERACTION",
+          weight: isHighEmotion ? 1 + emotionIntensity : 0.5,
+        },
+      });
+    }
+
+    this.workingMemory.clear(sessionId);
+  }
+}