EPIC: Structure playbook with spaces

[jracenet]

Description

Currently, all playbook entries (standards, commands, and skills) are stored and managed
at a global, flat organization level. This causes ownership and scaling issues.

This epic will introduce the concept of "spaces". Spaces are entities belonging to an
organization that contain their own playbook. They will allow teams to structure and
author their best practices in isolation.

Scope

⚠️ Warning: This epic will solely focus on playbook organization. It will not cover
things such as user rights regarding playbook authoring. ⚠️

This epic will cover the following capabilities:

• Spaces can be added to / removed from an organization
• Playbook entries can be managed within a space
• Playbook entries can be moved from one space to another
• Minimal space member management (invite / join…)
• Set space visibility: public (a space can be discovered by any member of the
  organization) / private (a member needs to be invited)
• New navbar enabling smooth navigation across multiple spaces