feat: 管理面板补齐(RAG导入/记忆添加/会话接history/诚实表述) + design/16 §4.6 IM多会话隔离+第三方身份+黑白名单

agent-98 面板批次:
- 会话管理面板改接 history.ListSessions(主web+次级) + 新建次级会话按钮
- 记忆面板手动添加入口 POST /admin/memories(owner)
- 知识库真正实现 IndexDocument(分块+落projectindex) + POST /admin/rag 导入端点
- 三面板空态诚实表述(去除'后端M10+提供')
- RAG嵌入降级到keyword/line(无直属embedder,不伪造语义,符合红线)

agent-99 design/16 §4.6:
- model.Message.SenderName + 迁移0006 sender_name 列
- 第三方身份边界: session.ResolveActor判定(非LLM猜) + [第三方·昵称]前缀(不改源content)
- 群聊/陌生人落独立sess-xxx(persistIsolated),不写主会话,不广播
- 黑/白名单(allowGroups/denyGroups/allowUsers/denyUsers)最前拦截,不进LLM
- 多账号 CHANNELS_JSON 配置 + 每平台多实例
- 管理只读 GET /admin/channels/{platform}/messages(该平台非主人消息流)

实机验证(JWT): 会话管理返回主会话web / 记忆添加成功 / RAG导入documents非空+Cyrene命中; 后端build/vet/test全绿 + 前端build绿

cmd/cyrene/wire.go

@@ -15,6 +15,7 @@ import (
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/bus"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/capability/mcp"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/capability/registry"
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/adapter"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/session"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
 	"git.yeij.top/AskaEth/Cyrene_v2/internal/db"
@@ -553,6 +554,12 @@ func (a *app) wireFrontend() error {
 		// `message_persisted` broadcast the orchestrator uses, so the Web client mirrors
 		// IM messages with one, uniform frame (design/16 §4.4).
 		a.channelBridge.SetOnPersisted(a.gw.BroadcastPersisted)
+		// design/16 §4.6 §6: a message dropped by the platform's allow/deny
+		// black-or-white lists is recorded in the gateway audit trail so the
+		// rejection is "audit 可查" even though it never reaches the loop.
+		a.channelBridge.SetOnRejected(func(msg adapter.UnifiedMessage, reason string) {
+			a.gw.AuditEvent("bridge:"+msg.Platform, "channel.reject", reason)
+		})
 	}
 	a.gw = gw
 	return nil