WIP: feat(team): support manual teammate management

[piorpua]

Summary

• Adds explicit Team leader validation and ordered provisioning for multi-member Team creation.
• Supports manual teammate add/remove flows with leader protection, mailbox notices, wake handling, and background runtime attach.
• Updates Team MCP tool contracts to return structured JSON and removes stale dynamic roster/catalog prompt injection.

Verification

• just push -u origin aionissue/task-20260706-002-001
• cargo fmt --all -- --check
• cargo clippy -p aionui-api-types -p aionui-team-prompts -p aionui-team -p aionui-app -- -D warnings
• cargo test -p aionui-api-types -p aionui-team-prompts -p aionui-team -p aionui-app
• cargo test --workspace

Notes

• No database migration is included.
• This is the backend companion for the AionUi Team manual teammate flow.
• Manual desktop verification is still recommended for active-session mailbox, wake, runtime attach, and MCP tool-call behavior.