test: move Vitest configs under test

ui/vitest.config.ts

@@ -1,6 +1,9 @@
 import { playwright } from "@vitest/browser-playwright";
 import { defineConfig, defineProject } from "vitest/config";
-import { jsdomOptimizedDeps, resolveDefaultVitestPool } from "../vitest.shared.config.ts";
+import {
+  jsdomOptimizedDeps,
+  resolveDefaultVitestPool,
+} from "../test/vitest/vitest.shared.config.ts";
 
 const sharedUiTestConfig = {
   isolate: true,

ui/vitest.node.config.ts

@@ -1,5 +1,5 @@
 import { defineConfig } from "vitest/config";
-import { resolveDefaultVitestPool } from "../vitest.shared.config.ts";
+import { resolveDefaultVitestPool } from "../test/vitest/vitest.shared.config.ts";
 
 // Node-only tests for pure logic (no Playwright/browser dependency).
 export default defineConfig({