feat: Footprint proof card

[pacphi]

Why

Show that ak stays out of projects that have not opted in (design: Proof that ak stays out of other projects).

In scope

Per-session akFootprint field; parse attachment and system records for hooks; compare opted-in and not, before and after.

Out of scope

Changing other projects.

Acceptance criteria

• Projects that have not opted in show zero ak calls, skills and hooks after the switch

Dependencies

Blocked by: #366

Blocks: #388

Plan

• Release: 4.0.0-beta.4
• Size: size:M · Workstream: ws:project-scope
• Epic: feat: project-scope P6, the dashboard for all work (epic) #301
• Card: P6-14 in the card inventory
• Sources: Design (docs(plans): project-scoped management design and its prerequisites #289) Proof that ak stays out of other projects

Verification

• node scripts/run-tests.mjs focus (new footprint tests)