feat(backthink/admin): ③b — rag/delete 真实现 + D1 推送出口钩子(自建优先→个推兜底) + api-reference 补 D2/D3/D5 补丁

- B5: POST /admin/rag/delete 真做(DeleteDocument→DeleteProject 级联删章节+索引清理, owner+审计, 200/404/500, 500降级兜底); users/iot scenarios+rules 诚实501(无用户表/IoT场景规则模型, 消息写明缺什么, 不伪造), 锁住 501+not_implemented
- D1: backthink/push_outlet.go PushExporter{Export}; pushOutlet 自建HTTP(2xx=送达, token仅Authorization头+error脱敏)优先→Getui兜底(未接入, 诚实日志'getui not integrated'+(false,nil)); backthink.Deps.Exporter → pusher.withExporter, Push 在WS/IM后 exportAsync(detached+5s超时, 失败仅日志, 不破坏现有投递, 限流不上报); config PushOutletConfig(PUSH_EXPORTER_* + GETUI_*占位)
- 前端 Rag.tsx/api.ts 删除后 reload + 类型; Docs/api-client v0.31 + api-reference(#23 owner/200-404, §8.4, 端点表PATCH/DELETE messages + pinned + messages?q=)
- 测试(push_outlet/admin_rag_delete/admin_honest501/knowledge store), 后端+前端build全绿+3平台交叉编译
- 刻意: Getui SDK 未接入(无SDK不硬造), 主人自建服务填 PUSH_EXPORTER_URL/TOKEN 即可

internal/runtime/knowledge/store_test.go

@@ -99,10 +99,56 @@ func TestIndexDocumentRequiresProjectStore(t *testing.T) {
 	}
 }
 
-func TestDeleteDocumentStillUnsupported(t *testing.T) {
+// TestDeleteDocumentRemovesProjectAndChapters proves delete is a real round-trip:
+// the document disappears from the list and the search, and deleting it again is
+// a not-found rather than a silent success.
+func TestDeleteDocumentRemovesProjectAndChapters(t *testing.T) {
 	t.Parallel()
-	s := New(Deps{Log: testLogger()})
-	if err := s.DeleteDocument(context.Background(), "any"); !errors.Is(err, ErrWriteUnsupported) {
-		t.Fatalf("DeleteDocument err = %v, want ErrWriteUnsupported", err)
+	ctx := context.Background()
+	s := newTestStore(t)
+	if err := s.IndexDocument(ctx, Doc{
+		ID:      "doc-1",
+		Name:    "Cyrene 设计",
+		Content: "第一段：项目描述。\n\n第二段：内部实现要点。",
+	}); err != nil {
+		t.Fatalf("IndexDocument: %v", err)
+	}
+
+	if err := s.DeleteDocument(ctx, "doc-1"); err != nil {
+		t.Fatalf("DeleteDocument: %v", err)
+	}
+	docs, err := s.ListDocuments(ctx)
+	if err != nil {
+		t.Fatalf("ListDocuments: %v", err)
+	}
+	if len(docs) != 0 {
+		t.Fatalf("documents = %+v, want empty after delete", docs)
+	}
+	hits, err := s.Search(ctx, "内部实现")
+	if err != nil {
+		t.Fatalf("Search: %v", err)
+	}
+	if len(hits) != 0 {
+		t.Fatalf("hits = %+v, want none after delete", hits)
+	}
+
+	if err := s.DeleteDocument(ctx, "doc-1"); !errors.Is(err, ErrDocumentNotFound) {
+		t.Fatalf("second DeleteDocument err = %v, want ErrDocumentNotFound", err)
+	}
+}
+
+func TestDeleteDocumentBlankIDNotFound(t *testing.T) {
+	t.Parallel()
+	s := newTestStore(t)
+	if err := s.DeleteDocument(context.Background(), "  "); !errors.Is(err, ErrDocumentNotFound) {
+		t.Fatalf("DeleteDocument blank id err = %v, want ErrDocumentNotFound", err)
+	}
+}
+
+func TestDeleteDocumentRequiresProjectStore(t *testing.T) {
+	t.Parallel()
+	s := New(Deps{Log: testLogger()}) // projects == nil
+	if err := s.DeleteDocument(context.Background(), "doc-1"); err == nil {
+		t.Fatal("DeleteDocument without a project index should error")
 	}
 }