feat(workhub): persist delegation linkage

[ARE404]

Summary

Persist the first Slice 5 delegation authority in the existing WorkHub Coordination Session:

• append closed, versioned delegation_intent and delegation_committed records around create_new and delegate_existing effects
• replay an exact committed result after Runtime Host restart, reject conflicting action-id reuse, and resume an interrupted intent without re-admitting an expired opaque candidate
• recover an accepted target Turn from durable root/message admission evidence when submit outcome is unknown
• project persisted target Session ids into the Desktop host namespace

This intentionally does not add replace, Stop ownership, target lifecycle state, or a general workflow phase machine. Those remain later Slice 5 work.

Refs #3492
Proposal: #3286

Design choice: minimal intent before the effect

A committed-only journal is insufficient because candidateRef is deliberately opaque and scoped to one candidate snapshot. If the target effect succeeds but the committed link is not appended before a Host restart, a later candidate set cannot safely reconstruct which Session the action selected.

The Action Gate therefore writes one immutable delegation_intent containing the resolved target before attempting the effect, then appends one immutable delegation_committed record with the accepted target Turn. This is the minimum recovery seam: the two records are append-only facts, not mutable phases, and they do not claim ownership of Stop or target execution lifecycle.

Verification

• npm -w packages/core test — PASS (658/658)
• WorkHub Action Gate, coordinator, and protocol tests — PASS (25/25)
• Runtime Host full test suite — PASS on exact head
• Desktop main-process full test suite — PASS on exact head
• affected Core/Storage/MCP/Runtime/Runtime Host builds and Desktop build:test — PASS
• Biome on all changed TypeScript files — PASS
• ASF header audit and git diff --check — PASS

npm run build reaches the unchanged @maka/ui workspace and stops on existing prop/type mismatches (settledText, conversationKey, unlockAutoFollow, and trailingAction). This PR does not modify packages/ui; all affected package builds and Desktop main build pass.

No screenshot or recording: this PR changes internal persistence/recovery behavior and adds no visual UI change.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Codex implemented the typed records, durable journal and recovery wiring, added tests and ADR updates, and ran the verification above. The commit includes the required Generated-by: Codex trailer.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

[ARE404]

Superseded by #3935. GitHub automatically closed this PR when the fork branch was renamed to satisfy CONTRIBUTING.md; the replacement contains the same Slice 5 work plus the production retry-identity P1 fix and complete verification matrix. — Codex