Add Trae superpowers bootstrap assets

[ice-zjchen]

Motivation

• Provide Trae users the same Superpowers onboarding and CLI experience currently available for Codex.
• Make it easy to discover, list, and load skills from ~/.trae using the same naming and tool-mapping conventions as other integrations.
• Ship a platform-specific CLI so bootstrap and skill loading work with Trae file locations and workflows.

Description

• Add .trae/INSTALL.md containing installation and verification instructions for Trae.
• Add .trae/superpowers-bootstrap.md with bootstrap instructions, tool mappings, skill naming rules, and mandatory workflow guidance.
• Add an executable .trae/superpowers-trae CLI that mirrors superpowers-codex and implements bootstrap, find-skills, and use-skill using ~/.trae paths and the shared lib/skills-core utilities.
• The CLI auto-loads superpowers:using-superpowers, reports update availability, and prints skill metadata and content without frontmatter.

Testing

• No automated tests were run for this change since it adds documentation and a platform-specific CLI script only.

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Codex Task