feat: project-scope P3, Codex and OpenCode project settings (epic) #298

Why

Design phase P3. The Codex part lands in beta.1 and OpenCode in beta.2 (master plan Decision 2).

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-P3 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.