[connector] Add ClickUp connector

[sabbah13]

ClickUp connector. Cursor primitive: date_updated + assignee filter.

API: https://clickup.com/api/clickupreference/operation/GetFilteredTeamTasks/
Endpoint: /team/{team_id}/task?assignees[]={user_id}&date_updated_gt={cursor}

Owner-first rule: assignees[] set to current user.

Files to create:

• packages/connector-issues-clickup/src/index.ts
• packages/connector-issues-clickup/src/auth.ts
• packages/connector-issues-clickup/test/contract.test.ts

Estimated effort: ~60 lines + 1 contract test.

[sabbah13]

Closing as already supported via Cowork's native MCP infrastructure (entry clickup in packages/plugin/.mcp.json).

To use ClickUp with Cowork Tasks: open Customize → Connectors in Cowork, find ClickUp, click Connect. Then run /cowork-tasks:triage-now.

Cowork Tasks does not maintain custom connector packages - it composes Cowork's hosted MCP servers, which handle auth, polling, and rate limiting upstream. See the new policy in CONTRIBUTING.md (landing in #38).