Add multi-llm-plugin

[beastlabai]

What this adds

One row in the Community Skills → Individual Skills table for multi-llm-plugin:

Multi-LLM orchestration plugin for Claude Code: parallel plan review, task generation, implementation, and code review across 12 coding harnesses (Codex, Cursor, opencode, pi, aider, Antigravity…)

Why it's valuable

It turns Claude Code into an orchestrator over the other CLI coding agents the user already has installed: fan out a plan review, task generation, an implementation run, a code review, or a free-text question to up to 12 harnesses in parallel, then get a consolidated comparison back. It goes well beyond a single SKILL.md: the skill ships provider adapter scripts, a providers config system, and an e2e test harness, and it is documented in the repo README (with a full video walkthrough).

• Prerequisites: Claude Code plus whichever of the supported harness CLIs (and their API keys/subscriptions) you want to fan out to — it uses your locally installed tools; no third-party server of ours is involved, and nothing routes through the submitter's infrastructure.
• License: MIT (declared in the plugin manifest).
• Install: /plugin marketplace add beastlabai/multi-llm-plugin, then /plugin install multi-llm.

Honest disclosures (please read before reviewing)

• Star count is below the threshold: the repo currently has 8 stars, under the 10-star social-proof minimum in CONTRIBUTING.md. I'm not inflating or hiding that; if the auto-close policy applies, I understand, and I'll resubmit once it crosses 10.
• AI assistance: this PR was prepared and submitted with the help of Claude Code, acting on my direction. CONTRIBUTING.md asks for PRs that are not explicitly AI-generated/submitted, so I'm flagging this openly rather than pretending otherwise — I'd rather be disqualified honestly than merged on a false pretense. The plugin itself is my own project, human-designed, tested end-to-end, and dogfooded daily.

All links in the added row were tested. One item per PR, formatted to match the existing table rows.