#7145: chore: update package description to reflect multi-channel capabilities

The previous description ('WhatsApp gateway CLI') was outdated given OpenClaw's current capabilities as a multi-channel agent runtime. Updated to reflect support for Telegram, Discord, Slack, MCP, etc. <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> Updates the root `package.json` package description to reflect OpenClaw’s current positioning as a multi-channel agent runtime (Telegram/Discord/Slack/WhatsApp, local tools, and MCP servers) instead of a WhatsApp-only gateway CLI. This affects the metadata users see on npm/GitHub and in package managers; no runtime code, dependencies, or build/test behavior changes. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge; it only changes package metadata text. - Single-line `package.json` description update with no code-path or dependency impact; low chance of regressions. - No files require special attention <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} **Context used:** - Context from `dashboard` - CLAUDE.md ([source](https://app.greptile.com/review/custom-context?memory=fd949e91-5c3a-4ab5-90a1-cbe184fd6ce8)) - Context from `dashboard` - AGENTS.md ([source](https://app.greptile.com/review/custom-context?memory=0d0c8278-ef8e-4d6c-ab21-f5527e322f13)) <!-- /greptile_comment -->