Implement `set_projects_completion` for Homogeneous Bulk Completion State

[deverman]

Summary

Implement set_projects_completion / focusrelay set-projects-completion for homogeneous bulk project lifecycle changes.

This tool owns project complete/uncomplete behavior and stays separate from set_projects_status.

Scope

Supported v1 states:

• completed
• active

Input:

• a list of project IDs
• one shared target state for all IDs

Out of scope:

• on-hold or dropped status changes
• project field patching
• project moves
• mixed per-item states in one request

Acceptance Criteria

• completing projects works for homogeneous bulk input
• uncompleting projects works for homogeneous bulk input
• project completion semantics match documented Omni Automation behavior
• verification confirms final project state after mutation
• CLI and MCP use the same request and result shape

Test Plan

• complete project
• uncomplete project
• invalid ID handling
• preview-only behavior
• verify readback behavior
• homogeneous bulk completion across multiple projects

Notes

done/completed belongs here, not in set_projects_status.