fix(hub): restore project create payload and stabilize integration DB seed

Explorer POST /projects was dropping projectId/folderId/workspaceDir after a
narrowed response shape, breaking admin-explorer. Make seedTestOrganization
idempotent under shared-DB isolation, force single-worker vitest, and align the
OAuth no-membership redirect expectation with authRoutes.

hub/test/integration/helpers.ts

@@ -80,42 +80,51 @@ export async function seedTestOrganization(
   id: string = DEFAULT_ORG_ID,
   slug: string = "test-default",
 ): Promise<void> {
+  // Serialise generate+inbox against concurrent callers in the same process.
+  // Integration tests share one DB and some files call seed without resetDb.
   await prisma.$transaction(async (tx) => {
-    await tx.organization.create({
-      data: {
-        id,
-        slug,
-        name: "Test Default Organization",
-        projectSettings: {
-          create: { membersCanCreateProjects: true },
-        },
-        agentRoles: {
-          create: {
-            id: `agent_role_draft_${id}`,
-            roleId: "draft",
-            label: "草稿",
-            sortOrder: 10,
-            isDefault: true,
+    const existing = await tx.organization.findUnique({
+      where: { id },
+      select: { id: true },
+    });
+    if (existing === null) {
+      await tx.organization.create({
+        data: {
+          id,
+          slug,
+          name: "Test Default Organization",
+          projectSettings: {
+            create: { membersCanCreateProjects: true },
+          },
+          agentRoles: {
+            create: {
+              id: `agent_role_draft_${id}`,
+              roleId: "draft",
+              label: "草稿",
+              sortOrder: 10,
+              isDefault: true,
+            },
           },
         },
-      },
+      });
+    }
+
+    const inbox = await tx.folder.findFirst({
+      where: { organizationId: id, kind: "SYSTEM_INBOX", archivedAt: null },
+      select: { id: true },
     });
+    if (inbox === null) {
+      await tx.folder.create({
+        data: {
+          id: `folder_inbox_${id}`,
+          organizationId: id,
+          name: "Inbox",
+          kind: "SYSTEM_INBOX",
+          sortKey: "000000",
+        },
+      });
+    }
   });
-  const inbox = await prisma.folder.findFirst({
-    where: { organizationId: id, kind: "SYSTEM_INBOX", archivedAt: null },
-    select: { id: true },
-  });
-  if (inbox === null) {
-    await prisma.folder.create({
-      data: {
-        id: `folder_inbox_${id}`,
-        organizationId: id,
-        name: "Inbox",
-        kind: "SYSTEM_INBOX",
-        sortKey: "000000",
-      },
-    });
-  }
 }
 
 /** A logger that discards everything (tests don't need fastify's pino). */