v0.8.71: Legacy follow-up and dead-code inventory: delete, wire, or track

[Hmbown]

Problem

The repo contains many intentional allow(dead_code) markers and old "follow-up" comments from previous release lanes. Some are legitimate compatibility or staged architecture surfaces; others may be stale promises, dead scaffolding, or missing issue links.

Before v0.9 expands workflow/Fleet surfaces further, CodeWhale should run a deliberate inventory pass: delete what is stale, wire what is ready, and track what must stay.

Scope

Audit follow-up/dead-code markers across active code and docs, especially:

• #[allow(dead_code)] without a current issue or clear rationale
• comments that name old follow-up releases but no longer map to an open tracker
• compatibility/deprecated tool surfaces that need planned-removal checks
• legacy DeepSeek/CodeWhale migration scaffolding that is still intentional vs stale
• tests or fixtures carrying old milestone branches as active-looking examples

Suggested Implementation

• Produce an inventory grouped by: delete now, wire now, keep with issue, defer to v0.9, historical docs only.
• Prefer small PRs by module rather than one giant cleanup.
• Preserve replay compatibility and documented legacy behavior.
• Add checks only for active policy/code paths, not changelog/archive text.

Acceptance Criteria

• Every remaining non-test allow(dead_code) in core TUI/runtime/provider surfaces has a current rationale or issue reference.
• Stale follow-up comments from old milestones are either removed, updated, or linked to live issues.
• Deprecated/hidden compatibility surfaces have explicit planned-removal or replay-support policy.
• Historical docs remain readable without being mistaken for current guidance.
• The cleanup does not change public behavior except where explicitly verified.