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/src/state.rs

@@ -0,0 +1,52 @@
+use std::time::Duration;
+
+use moka::sync::Cache;
+use sea_orm::DatabaseConnection;
+
+use erp_core::error::{AppError, AppResult};
+use erp_core::events::EventBus;
+
+use crate::engine::PluginEngine;
+
+/// 插件模块共享状态 — 用于 Axum State 提取
+#[derive(Clone)]
+pub struct PluginState {
+    pub db: DatabaseConnection,
+    pub event_bus: EventBus,
+    pub engine: PluginEngine,
+    /// Schema 缓存 — key: "{plugin_id}:{entity_name}:{tenant_id}"
+    pub entity_cache: Cache<String, EntityInfo>,
+}
+
+/// 缓存的实体信息
+#[derive(Clone, Debug)]
+pub struct EntityInfo {
+    pub table_name: String,
+    pub schema_json: serde_json::Value,
+    pub generated_fields: Vec<String>,
+}
+
+impl EntityInfo {
+    /// 从 schema_json 解析字段列表
+    pub fn fields(&self) -> AppResult<Vec<crate::manifest::PluginField>> {
+        let entity_def: crate::manifest::PluginEntity =
+            serde_json::from_value(self.schema_json.clone())
+                .map_err(|e| AppError::Internal(format!("解析 entity schema 失败: {}", e)))?;
+        Ok(entity_def.fields)
+    }
+}
+
+impl PluginState {
+    pub fn new(db: DatabaseConnection, event_bus: EventBus, engine: PluginEngine) -> Self {
+        let entity_cache = Cache::builder()
+            .max_capacity(1000)
+            .time_to_idle(Duration::from_secs(300))
+            .build();
+        Self {
+            db,
+            event_bus,
+            engine,
+            entity_cache,
+        }
+    }
+}