test(harness): migrate and exercise dev-chat-e2e from Claude Code and Codex

## Parent
- #436

## Goal
Prove the same persistent `dev-chat-e2e` role can be launched by a human in either Claude Code or Codex and consume an assigned coordination task through one Directory identity.

## Scope
- Document exact human launch commands/prompts for both tools.
- Dry-run and then exercise bootstrap, identity verification, private inbox, ACK, issue lease, heartbeat, and handoff on both surfaces.
- Migrate the existing local credential mapping atomically without exposing or rotating a valid token.
- Capture redacted evidence that both launches resolve to the same Directory ULID and never run concurrently.

## Acceptance
- Claude Code and Codex instructions are reproducible from a clean checkout.
- Both surfaces consume the same assignment protocol using one stable role and one Directory identity.
- Duplicate concurrent launch fails closed.
- Evidence contains no credential material.
- Do not start coordination Task #44 as part of this issue; use an explicitly assigned test task/fixture approved by coord-main.
- `./init.sh` passes.

## Dependencies
- #436
- all portable role runtime children
- Task #39 / issue #435 assignment supplied by coord-main

Start with parent issue #436 and the existing dev-chat-e2e role and portable runtime children. Reproduce the documented Claude Code and Codex launches from a clean checkout, using an explicitly assigned test task or fixture from coord-main rather than Task #44. Exercise the listed bootstrap, identity, inbox, lease, heartbeat, and handoff steps, then run ./init.sh and verify the redacted evidence and duplicate-launch behavior.

Written by the indexing model from the issue text.