v0.19.0

Custom Task ID Support

All commands that accept task IDs now work with ClickUp custom task IDs (the PREFIX-DIGITS format like PROJ-123 or DEV-42). Detection is automatic based on format - no flags or config changes needed.

cu task PROJ-123
cu update DEV-42 --status done
cu comment ENG-100 "shipping it"
cu time start PROJ-456
cu open PROJ-123

When a custom task ID is detected, the CLI appends custom_task_ids=true and team_id to the API request. The teamId from your config (already required) is used for resolution. Native alphanumeric IDs continue to work as before.

This covers all 20 commands that accept task IDs, including time tracking, dependencies, links, checklists, attachments, and custom fields.

Closes #13.

512 tests across 43 files.