Migrate Flow CLI skill to public repo

[peterargue]

Summary

Migrate the Flow CLI skill from the internal plugins repo to this public repository.

Context

The Flow CLI skill currently lives in the internal flow-claude-code-plugins repo. As part of the effort to create a single centralized public skills repository, it needs to be migrated here. This enables community access and contribution.

Acceptance Criteria

• Flow CLI skill migrated from internal repo to this repository
• Skill functionality verified after migration
• Internal repo updated to point to the new location
• README or docs updated to reflect the new home

References

• Internal Flow CLI skill
• Related: Peter's Flow CLI MCP PR #2306
• Discussed in AI tooling sync (Mar 19, Mar 25)