feat(skills): add MiniMax-AI/cli as default skill tap

[octo-patch]

Summary

• Add MiniMax-AI/cli (skill/ path) to DEFAULT_INSTALLER_SKILL_PACKS in backend/app/services/organizations.py so the mmx-cli skill is provisioned out of the box for every new organization
• Users can sync the pack from the Skills Marketplace UI — the SKILL.md is fetched directly from MiniMax-AI/cli
• Skill updates are fully decoupled: MiniMax maintains the upstream SKILL.md, no changes needed in this project

5 lines changed, 0 new files.

What is mmx-cli?

mmx-cli is a CLI tool for the MiniMax AI platform, providing:

• Text generation (MiniMax-M2.7 model)
• Image generation (image-01)
• Video generation (Hailuo-2.3)
• Speech synthesis (speech-2.8-hd, 300+ voices)
• Music generation (music-2.6, with lyrics, cover, and instrumental)
• Web search

The SKILL.md follows the agentskills.io standard and includes agent-specific flags (--non-interactive, --quiet, --output json).

Test plan

• New organization provisioning includes the mmx-cli pack in the default skill pack list
• Syncing the pack discovers and registers the mmx-cli skill in the marketplace
• Ask agent "generate a jazz instrumental" — agent invokes mmx music generate via terminal