test(web): standardize frontend tests on Vitest (#6569)

* test(web): standardize frontend tests on Vitest

- configure Vitest, jsdom, and React Testing Library with shared test scripts.
- migrate existing node:test suites to the Vitest runner.
- rewrite JsonCodeEditor component tests with RTL and remove the direct happy-dom dependency.

* fix(ci): run frontend tests with Vitest

- invoke the configured Vitest script so browser test setup loads in CI.
- migrate remaining node:test suites to Vitest lifecycle APIs.

* test(web): use shared jsdom environment for component tests

- migrate usage cost and tool price tests to React Testing Library.
- remove duplicate happy-dom globals and rely on the configured Vitest setup.

* test(web): verify behavior with shared vitest setup

- replace Node test assertions with Vitest expect across frontend suites.
- migrate Keys component tests to React Testing Library interactions.
- centralize jsdom browser mocks for consistent component execution.

* fix(web): unblock frozen installs and Vitest CI

- sync dompurify 3.4.13 metadata into the Bun lockfile.
- replace the bun:test and happy-dom redemption harness with Vitest and RTL.
- preserve quota conversion, error feedback, and stale-response coverage in jsdom.

web/package.json

@@ -11,6 +11,8 @@
     "lint": "oxlint -c .oxlintrc.json .",
     "lint:fix": "oxlint -c .oxlintrc.json . --fix",
     "preview": "rsbuild preview",
+    "test": "vitest run",
+    "test:watch": "vitest",
     "format:check": "node scripts/format-with-protected-headers.mjs --check",
     "format": "node scripts/format-with-protected-headers.mjs --write",
     "copyright:check": "node scripts/add-copyright.mjs --check",
@@ -85,17 +87,21 @@
     "@tanstack/react-query-devtools": "^5.101.2",
     "@tanstack/react-router-devtools": "^1.167.0",
     "@tanstack/router-plugin": "^1.168.19",
+    "@testing-library/jest-dom": "^7.0.0",
+    "@testing-library/react": "^16.3.2",
+    "@testing-library/user-event": "^14.6.1",
     "@types/node": "^26.1.0",
     "@types/react": "^19.2.17",
     "@types/react-dom": "^19.2.3",
     "@typescript/native-preview": "^7.0.0-dev.20260702.3",
     "@xyflow/react": "^12.11.1",
     "embla-carousel-react": "^8.6.0",
-    "happy-dom": "^20.11.1",
+    "jsdom": "^29.1.1",
     "knip": "^6.24.0",
     "oxfmt": "^0.57.0",
     "oxlint": "^1.72.0",
-    "shadcn": "^4.12.0"
+    "shadcn": "^4.12.0",
+    "vitest": "^4.1.10"
   },
   "overrides": {
     "brace-expansion": "2.1.1",