feat: 完成 K 群組 — 對話模式：群聊與角色自聊

群聊/自聊子系統（apps/api/src/room/）：在場者名冊與共用場景記錄（純記憶體，
同 C-1 工作記憶的設計）、發言權分配（點名/話題相關度/性格基線/情緒/角色間
關係/發言冷卻與冷落累積算衝動值）、群聊矜持（重用 G-3 親密度分層模板、
下修有效親密度而非另建模板庫）、隱私邊界（EpisodicMemory.isPrivate ＋
KeywordMemoryRetriever.excludePrivate，天然呆為口風不緊例外）、群聊記憶
投影（各角色依自身視角固化，被虧的那位權重較高）、角色自聊（沿用發言權
機制、空轉偵測注入轉折或收尾、輪數硬上限、使用者插話切換群聊）。
新增 CharacterRelationship 表供角色間關係使用。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

prisma/migrations/20260813065157_add_room_and_privacy/migration.sql

@@ -0,0 +1,41 @@
+-- CreateTable
+CREATE TABLE "character_relationships" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "characterId" TEXT NOT NULL,
+    "otherCharacterId" TEXT NOT NULL,
+    "affinity" INTEGER NOT NULL DEFAULT 50,
+    "dynamic" TEXT,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" DATETIME NOT NULL,
+    CONSTRAINT "character_relationships_characterId_fkey" FOREIGN KEY ("characterId") REFERENCES "characters" ("id") ON DELETE CASCADE ON UPDATE CASCADE,
+    CONSTRAINT "character_relationships_otherCharacterId_fkey" FOREIGN KEY ("otherCharacterId") REFERENCES "characters" ("id") ON DELETE CASCADE ON UPDATE CASCADE
+);
+
+-- RedefineTables
+PRAGMA defer_foreign_keys=ON;
+PRAGMA foreign_keys=OFF;
+CREATE TABLE "new_episodic_memories" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "characterId" TEXT NOT NULL,
+    "content" TEXT NOT NULL,
+    "occurredAt" DATETIME NOT NULL,
+    "emotionTag" TEXT NOT NULL,
+    "emotionIntensity" REAL NOT NULL,
+    "retrievalCount" INTEGER NOT NULL DEFAULT 0,
+    "lastRetrievedAt" DATETIME,
+    "source" TEXT NOT NULL,
+    "weight" REAL NOT NULL DEFAULT 1,
+    "relatedUserId" TEXT,
+    "isPrivate" BOOLEAN NOT NULL DEFAULT false,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT "episodic_memories_characterId_fkey" FOREIGN KEY ("characterId") REFERENCES "characters" ("id") ON DELETE CASCADE ON UPDATE CASCADE,
+    CONSTRAINT "episodic_memories_relatedUserId_fkey" FOREIGN KEY ("relatedUserId") REFERENCES "users" ("id") ON DELETE SET NULL ON UPDATE CASCADE
+);
+INSERT INTO "new_episodic_memories" ("characterId", "content", "createdAt", "emotionIntensity", "emotionTag", "id", "lastRetrievedAt", "occurredAt", "relatedUserId", "retrievalCount", "source", "weight") SELECT "characterId", "content", "createdAt", "emotionIntensity", "emotionTag", "id", "lastRetrievedAt", "occurredAt", "relatedUserId", "retrievalCount", "source", "weight" FROM "episodic_memories";
+DROP TABLE "episodic_memories";
+ALTER TABLE "new_episodic_memories" RENAME TO "episodic_memories";
+PRAGMA foreign_keys=ON;
+PRAGMA defer_foreign_keys=OFF;
+
+-- CreateIndex
+CREATE UNIQUE INDEX "character_relationships_characterId_otherCharacterId_key" ON "character_relationships"("characterId", "otherCharacterId");

prisma/schema.prisma

@@ -134,10 +134,29 @@ model Character {
   scheduleExceptions  ScheduleExceptionLog[]
   tasks               Task[]
   proactiveCareLogs   ProactiveCareLog[]
+  relationshipsToOthers   CharacterRelationship[] @relation("RelationshipFrom")
+  relationshipsFromOthers CharacterRelationship[] @relation("RelationshipTo")
 
   @@map("characters")
 }
 
+// K-2/K-4 角色間關係：群聊中「角色間關係上場」與發言權分配的「與發言者的關係」都吃這張表。
+// 有向邊（characterId 對 otherCharacterId 的觀感），故同作品兩角色互相的觀感可以不對稱。
+model CharacterRelationship {
+  id              String    @id @default(cuid())
+  characterId     String
+  character       Character @relation("RelationshipFrom", fields: [characterId], references: [id], onDelete: Cascade)
+  otherCharacterId String
+  otherCharacter  Character @relation("RelationshipTo", fields: [otherCharacterId], references: [id], onDelete: Cascade)
+  affinity        Int       @default(50) // 0~100，越高越要好；50 為中性
+  dynamic         String? // 互動基調描述性標籤，例如 loyal-friend／rival／protective／crush
+  createdAt       DateTime  @default(now())
+  updatedAt       DateTime  @updatedAt
+
+  @@unique([characterId, otherCharacterId])
+  @@map("character_relationships")
+}
+
 // G-4 反差萌稀有度控制：記錄每次反差行為觸發的時間，供冷卻期判定。
 model ContrastTriggerLog {
   id          String   @id @default(cuid())
@@ -210,6 +229,7 @@ model EpisodicMemory {
   weight           Float        @default(1) // 權重（供遺忘／檢索排序使用）
   relatedUserId    String? // 這段記憶與哪位使用者相關（E-5 關係加權檢索用）
   relatedUser      User?        @relation(fields: [relatedUserId], references: [id], onDelete: SetNull)
+  isPrivate        Boolean      @default(false) // K-3 隱私邊界：一對一聊過的私密內容，群聊中不主動洩漏（口風不緊原型除外）
   createdAt        DateTime     @default(now())
 
   @@map("episodic_memories")