修复: AI 删项目改软删 + 补回收站三工具 + list_projects 排除回收站

- delete_project 由 repo.delete 物理删改 soft_delete（与 UI 删一致）
- 新增 restore_project / purge_project / list_trash 三工具（复用 ProjectRepo 回收站方法）
- list_projects 改 list_active 排除回收站，防 LLM 看到已删项目继续操作

Sprint 20 审查 ①② + Workflow A 验证发现 list_projects 泄漏

src-tauri/src/commands/ai/tool_registry.rs

@@ -85,7 +85,7 @@ pub fn build_ai_tool_registry(db: &Arc<Database>) -> AiToolRegistry {
             let db = db.clone();
             Box::pin(async move {
                 let repo = df_storage::crud::ProjectRepo::new(&db);
-                let mut items = repo.list_all().await?;
+                let mut items = repo.list_active().await?; // list_active 排除回收站(deleted_at)，防 LLM 看到已软删项目
                 items.truncate(50); // 防 LLM context 膨胀
                 Ok(serde_json::to_value(items)?)
             })
@@ -253,18 +253,57 @@ pub fn build_ai_tool_registry(db: &Arc<Database>) -> AiToolRegistry {
 
     // ── 高风险 (High) ──
     registry.register(
-        "delete_project", "删除项目及其所有关联数据",
+        "delete_project", "删除项目（移入回收站，可恢复。永久删除用 purge_project）",
         df_ai::ai_tools::object_schema(vec![("id", "string", true)]), RiskLevel::High,
         { let db = db.clone(); Box::new(move |args: serde_json::Value| {
             let db = db.clone();
             Box::pin(async move {
                 let id = args["id"].as_str().ok_or_else(|| anyhow::anyhow!("缺少 id"))?;
                 let repo = df_storage::crud::ProjectRepo::new(&db);
-                let deleted = repo.delete(id).await?;
+                let deleted = repo.soft_delete(id).await?;
                 Ok(serde_json::json!({ "deleted": deleted, "id": id }))
             })
         })},
     );
+    registry.register(
+        "restore_project", "从回收站恢复已删除项目",
+        df_ai::ai_tools::object_schema(vec![("id", "string", true)]), RiskLevel::High,
+        { let db = db.clone(); Box::new(move |args: serde_json::Value| {
+            let db = db.clone();
+            Box::pin(async move {
+                let id = args["id"].as_str().ok_or_else(|| anyhow::anyhow!("缺少 id"))?;
+                let repo = df_storage::crud::ProjectRepo::new(&db);
+                let restored = repo.restore(id).await?;
+                Ok(serde_json::json!({ "restored": restored, "id": id }))
+            })
+        })},
+    );
+    registry.register(
+        "purge_project", "永久删除项目及关联数据（不可恢复）",
+        df_ai::ai_tools::object_schema(vec![("id", "string", true)]), RiskLevel::High,
+        { let db = db.clone(); Box::new(move |args: serde_json::Value| {
+            let db = db.clone();
+            Box::pin(async move {
+                let id = args["id"].as_str().ok_or_else(|| anyhow::anyhow!("缺少 id"))?;
+                let repo = df_storage::crud::ProjectRepo::new(&db);
+                let purged = repo.purge_with_descendants(id).await?;
+                Ok(serde_json::json!({ "purged": purged, "id": id }))
+            })
+        })},
+    );
+    registry.register(
+        "list_trash", "列出回收站已删除项目",
+        df_ai::ai_tools::object_schema(vec![]), RiskLevel::Low,
+        { let db = db.clone(); Box::new(move |_args: serde_json::Value| {
+            let db = db.clone();
+            Box::pin(async move {
+                let repo = df_storage::crud::ProjectRepo::new(&db);
+                let mut items = repo.list_deleted().await?;
+                items.truncate(50); // 防 LLM context 膨胀
+                Ok(serde_json::to_value(items)?)
+            })
+        })},
+    );
     registry.register(
         "run_workflow", "运行指定的工作流 DAG",
         df_ai::ai_tools::object_schema(vec![("name", "string", true), ("dag", "object", true)]), RiskLevel::High,