Refactor roadmap: ownership map and extraction plan

[Hmbown]

Scope

Create the ownership map for the refactor thread before more cockpit/tool/workbench code lands. This is the maintainer-grade factorization audit for v0.8.42.

Acceptance

• Map each high-churn surface to its current owner and desired owner: sidebar/cockpit, command receipts, task/workbench state, control-plane actions, tool registry/studio, continuity/cache, config/settings, docs.
• Identify duplicated calculations and render-model drift, starting with the v0.8.41 cockpit Budget/Now duplication.
• Produce a small table: source of truth, projection helpers, UI owners, tests, target milestone.
• Create follow-up issues only when the desired boundary is clear.

Rule

No abstract cleanup. Every refactor item must remove duplication, make testing easier, or define a boundary needed by v0.8.43-v0.8.48.

[Hmbown]

This is valuable as a maintainer map, but it is not a release-testable v0.8.42 blocker. Moving it to v0.8.43 as a planning artifact for the truth-surface/refactor pass; the useful acceptance criteria remain the ownership table, source-of-truth map, and follow-up issues only where boundaries are clear.