feat: project-scope P4, Brain, agent-browser, embeddings and Superpowers (epic) #299

Why

Design phase P4.

In scope

The child cards listed under this epic.

Out of scope

Work on other phases.

Acceptance criteria

• Every child card is closed

Dependencies

Blocked by: None

Blocks: None

Plan

• Release: 4.0.0-beta.2
• Workstream: ws:project-scope
• Card: EP-P4 in the card inventory
• Sources: Design (docs(plans): project-scoped management design and its prerequisites #289) Phasing; Master plan (docs(plans): v4 GA master plan, supersession ledger and v5 registers #290) Release train

Verification

Every child card is closed.