chore: fix vitest standalone configs and update package description

- vitest.live.config.ts and vitest.e2e.config.ts now extend root config
- Inherits testTimeout (120s), resolve.alias, pool, setupFiles, excludes
- ui/vitest.node.config.ts gets explicit 120s timeout
- package.json description updated for multi-channel AI gateway
- Removed unused src/utils/time-format.ts

ui/vitest.node.config.ts

@@ -3,6 +3,7 @@ import { defineConfig } from "vitest/config";
 // Node-only tests for pure logic (no Playwright/browser dependency).
 export default defineConfig({
   test: {
+    testTimeout: 120_000,
     include: ["src/**/*.node.test.ts"],
     environment: "node",
   },