#39584 refactor: Migrate livechat/users endpoints to OpenAPI with AJV validation

Proposed changes

Migrates the livechat/users/:type and livechat/users/:type/:_id endpoints from the legacy addRoute() pattern to the new OpenAPI-compatible chained route pattern with inline AJV validation schemas.

Resolves: https://github.com/RocketChat/Rocket.Chat-Open-API/issues/150

Changes

apps/meteor/app/livechat/imports/server/rest/users.ts

• Replaced legacy API.v1.addRoute() calls with the new chained API.v1.get().post().get().delete() pattern
• Added inline AJV validation schemas for query params, request body, and responses (200/400/401/403)
• Used ExtractRoutesFromAPI + declare module augmentation for type extraction
• All 4 endpoints migrated: GET /livechat/users/:type, POST /livechat/users/:type, GET /livechat/users/:type/:_id, DELETE /livechat/users/:type/:_id

packages/rest-typings/src/v1/omnichannel.ts

• Removed parameterized path types (/livechat/users/${string}, /livechat/users/${string}/${string}) that were previously in the shared Endpoints interface
• Kept concrete path aliases (e.g., /livechat/users/agent) for client-side useEndpoint() compatibility

.changeset/migrate-livechat-users-openapi.md

• Added changeset with minor bump for @rocket.chat/meteor and @rocket.chat/rest-typings

Test results

Summary by CodeRabbit

• New Features

  • OpenAPI-backed request/response validation for livechat user endpoints.
  • Separate manager and user routes with create, list, fetch-by-id, and delete actions; create now accepts a simple username payload.

• Refactor

  • Routes reorganized for clearer manager/user separation, improved pagination, filtering, and sensible defaults.
  • Stronger authorization checks and clearer error responses; single-user fetch may return null when not found.