[connector] Add Jira (Atlassian) connector

[sabbah13]

Jira (Cloud and Server) connector. Cursor primitive: updated field via JQL.

API: https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-issue-search/
JQL: assignee = currentUser() AND updated > -7d ORDER BY updated DESC (filter to user's items only).

Auth: Atlassian OAuth 2.0 (3LO).

Files to create:

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

Owner-first rule: filter assignee = currentUser(). Skip status-watching subscriptions.

Estimated effort: ~80 lines + 1 contract test.

[sabbah13]

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

To use Atlassian (Jira) with Cowork Tasks: open Customize → Connectors in Cowork, find Atlassian (Jira), 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).