Added all rocket chat rest api's and plugin core

[dodaa08]

Summary

Rocket.Chat channel plugin rewrite REST client + OpenClaw plugin core.

Changes

File	What
src/client.ts	Full RC REST API client — postMessage, listRooms, syncMessages, subscriptions, threads, file upload/download, rate-limit handling
src/plugin.ts	Channel plugin — multi-account resolveAccount/listAccountIds, outbound sendText, startGateway lifecycle (abortSignal)
src/config.ts	Zod-validated multi-account schema (token/password auth, polling transport, env var substitution)
src/index.ts	Clean register/activate pattern; removed inline webhook handler
openclaw.plugin.json	Channel manifest with multi-account JSON Schema, kind: "channel"
types/types.ts	Consolidated type definitions
package.json	Added zod dep, entry → ./src/index.ts

Verification

• Outbound: POST /tools/invoke → sendText → message delivered to GENERAL
• Registration: openclaw channels status shows Rocket.Chat main: enabled, configured, running
• Config: Zod schema validates multi-account config with env var interpolation

Remaining

• Inbound polling (next PR)
• Clean up stale npm-installed plugin entry from global manifest (cosmetic warning)