Add support for Linear initiatives

[ryanrozich]

Summary

Add support for Linear initiatives to linearis, enabling users to manage strategic planning hierarchies (Initiatives → Projects → Issues) via CLI with structured JSON output.

Motivation

Initiatives are Linear's top-level organizational construct for grouping related projects. Users who manage their Linear workflows through linearis currently cannot:

• Query or list initiatives
• Create or update initiatives programmatically
• Track initiative progress through automation
• Access the complete Linear hierarchy via CLI

This forces users to use the Linear UI for strategic planning, breaking CLI-based workflows.

Proposed Commands

Core Operations

• linearis initiatives list - List all initiatives with filtering
• linearis initiatives read <id|name> - Get initiative details with projects
• linearis initiatives create <name> - Create new initiative
• linearis initiatives update <id|name> - Update existing initiative
• linearis initiatives archive <id|name> - Archive initiative (soft delete)
• linearis initiatives delete <id|name> - Permanently delete initiative

Key Features

• Smart ID resolution (accepts names or UUIDs)
• Team-scoped name disambiguation
• Full metadata support (dates, colors, icons, status, progress)
• Nested project relationships
• Consistent JSON output

Example Usage

# List active initiatives
linearis initiatives list

# Create Q2 initiative
linearis initiatives create "Q2 2025 Mobile Apps" \
  --description "Launch iOS and Android apps" \
  --target-date 2025-06-30 \
  --color "#4285F4"

# Read with projects
linearis initiatives read "Q2 2025 Mobile Apps" --projects-first 10

# Update status
linearis initiatives update "Q2 2025 Mobile Apps" --status "in_progress"

Implementation Notes

- Follows existing project-milestones command pattern
- Uses GraphQL API (initiatives fully supported)
- Requires Linear premium subscription
- Estimated effort: 4-6 hours

References

- Linear Initiatives Docs: https://linear.app/docs/initiatives

[itissid]

I've added #25 as a part of my itissid/humanlayer slash commands (see itissid/humanlayer#3) for claude code.