Version: 0.9.74.dev.260505

后端：
1.阶段 6 memory 服务化 CP1-CP3 落地
- 新增 cmd/memory 独立进程入口，落地 services/memory dao/rpc/sv 与 memory zrpc pb
- 将 memory.extract.requested outbox 消费与 memory worker 迁入 cmd/memory，单体 worker 不再消费 memory outbox
- 新增 gateway/client/memory、shared/contracts/memory 和 shared/ports memory port
- 将 /api/v1/memory/items* HTTP 管理面切到 memory zrpc，gateway 只保留鉴权、限流、幂等、参数绑定和响应透传
- 新增 memory Retrieve RPC，并将 agent 主链路 memory reader 切到 memory zrpc 读取
- 补充 agent memory RPC reader 适配器，保留注入侧 observer / metrics 观测能力
- 保留旧 backend/memory 核心实现作为迁移期复用与回退面，cmd/memory 内部继续复用既有 Module / ReadService 逻辑
- 补充 memory.rpc 示例配置，更新单体 outbox 发布边界与 memory handler 注释口径

backend/services/memory/rpc/memory.proto

@@ -0,0 +1,27 @@
+syntax = "proto3";
+
+package smartflow.memory;
+
+option go_package = "github.com/LoveLosita/smartflow/backend/services/memory/rpc/pb";
+
+service Memory {
+  rpc Ping(StatusResponse) returns (StatusResponse);
+  rpc Retrieve(JSONRequest) returns (JSONResponse);
+  rpc ListItems(JSONRequest) returns (JSONResponse);
+  rpc GetItem(JSONRequest) returns (JSONResponse);
+  rpc CreateItem(JSONRequest) returns (JSONResponse);
+  rpc UpdateItem(JSONRequest) returns (JSONResponse);
+  rpc DeleteItem(JSONRequest) returns (JSONResponse);
+  rpc RestoreItem(JSONRequest) returns (JSONResponse);
+}
+
+message JSONRequest {
+  bytes payload_json = 1;
+}
+
+message JSONResponse {
+  bytes data_json = 1;
+}
+
+message StatusResponse {
+}