chore: fix vitest standalone configs and update package description (#11865)

* 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

* chore: filter inherited excludes in live/e2e vitest configs

* refactor: dedupe GroupPolicy/DmPolicy in extensions

Import from openclaw/plugin-sdk instead of re-declaring identical types.

src/utils/time-format.ts

@@ -1,6 +0,0 @@
-import { formatRelativeTimestamp } from "../infra/format-time/format-relative.ts";
-
-/** Delegates to centralized formatRelativeTimestamp with date fallback for >7d. */
-export function formatRelativeTime(timestamp: number): string {
-  return formatRelativeTimestamp(timestamp, { dateFallback: true, fallback: "unknown" });
-}