feat: initialize Nuanji (Warm Notes) project

- Base platform from base.git (ERP base: auth, core, config, message, workflow, plugin)
- Created erp-diary module skeleton (lib.rs, dto.rs, error.rs, event.rs, state.rs)
- Integrated erp-diary into workspace and erp-server
- Added DiaryModule registration in main.rs
- Added DiaryState FromRef in state.rs
- Diary routes mounted (empty routes, ready for implementation)
- Product design spec v1.2 preserved in docs/
- Implementation plan preserved in plans/

Cargo check: OK
Cargo test: OK (78+ base tests passing)

crates/erp-plugin/wit/plugin.wit

@@ -0,0 +1,54 @@
+package erp:plugin;
+
+/// 宿主暴露给插件的 API（插件 import 这些函数）
+interface host-api {
+    /// 插入记录（宿主自动注入 tenant_id, id, created_at 等标准字段）
+    db-insert: func(entity: string, data: list<u8>) -> result<list<u8>, string>;
+
+    /// 查询记录（自动注入 tenant_id 过滤 + 软删除过滤）
+    db-query: func(entity: string, filter: list<u8>, pagination: list<u8>) -> result<list<u8>, string>;
+
+    /// 更新记录（自动检查 version 乐观锁）
+    db-update: func(entity: string, id: string, data: list<u8>, version: s64) -> result<list<u8>, string>;
+
+    /// 软删除记录
+    db-delete: func(entity: string, id: string) -> result<_, string>;
+
+    /// 发布领域事件
+    event-publish: func(event-type: string, payload: list<u8>) -> result<_, string>;
+
+    /// 读取系统配置
+    config-get: func(key: string) -> result<list<u8>, string>;
+
+    /// 写日志（自动关联 tenant_id + plugin_id）
+    log-write: func(level: string, message: string);
+
+    /// 获取当前用户信息
+    current-user: func() -> result<list<u8>, string>;
+
+    /// 检查当前用户权限
+    check-permission: func(permission: string) -> result<bool, string>;
+
+    /// 根据编号规则生成下一个编号（如 INV-2026-0001）
+    numbering-generate: func(rule-key: string) -> result<string, string>;
+
+    /// 读取插件配置项
+    setting-get: func(key: string) -> result<list<u8>, string>;
+}
+
+/// 插件导出的 API（宿主调用这些函数）
+interface plugin-api {
+    /// 插件初始化（加载时调用一次）
+    init: func() -> result<_, string>;
+
+    /// 租户创建时调用
+    on-tenant-created: func(tenant-id: string) -> result<_, string>;
+
+    /// 处理订阅的事件
+    handle-event: func(event-type: string, payload: list<u8>) -> result<_, string>;
+}
+
+world plugin-world {
+    import host-api;
+    export plugin-api;
+}