Plugin system for custom integrations

[MeisnerDan]

Design and implement a plugin system that allows developers to extend Mission Control with custom integrations, workflows, and UI components. Plugins could add Slack notifications, Notion sync, time tracking integrations, or custom report generation. This opens Mission Control to community innovation without bloating the core codebase.

Acceptance Criteria

• Plugin manifest format (JSON schema) with metadata, hooks, permissions
• Hook system: allow plugins to subscribe to events (task created, completed, etc.)
• Plugin API: expose safe APIs for reading/writing tasks, logging activity
• Plugins sandboxed: limited access to user data, cannot execute arbitrary code
• Plugin discovery: plugin registry or marketplace (GitHub repo or npm package)
• Installation: CLI command to install plugins (e.g., mission-control install plugin-name)
• Settings: UI for configuring installed plugins and granting permissions
• Documentation: plugin development guide with examples
• Example plugin: e.g., Slack notification plugin to demonstrate the system
• Security: code review process, versioning, revocation of malicious plugins