fix(tickets): preserve compound read continuation

[BjRo]

Why

Closes #208. The read-ticket skill ended compound requests after retrieval, preventing separately authorized follow-on work.

What changed

Updated TM-R3 and TM-R4 plus the read-ticket workflow so retrieval-only responses remain verbatim while compound requests retain the exact ticket stream, return continuation to the enclosing owner, and keep ticket-body instructions untrusted. Added a cross-host read-and-implement eval with exact retrieval, tracker-protocol, repository-state, and semantic result checks. Bumped darrow-tickets-github to 0.4.3 in both manifests.

Verification

• read-ticket compound-continuation: passed 1/1 on Codex gpt-5.6-terra medium and Claude Sonnet 5 medium
• read-ticket direct-id: passed 1/1 on both Codex and Claude
• read-ticket missing-ticket: passed 1/1 on Claude; the current candidate also passed on Codex before the final compound-only wording adjustment
• all 14 read-ticket cases dry-prepared successfully
• skill inspector, bun run lint, bun run lint:ts, bun run lint:shell, bun run typecheck, bun run check:decisions, bun run check:docs, bun run eval:coverage, and fresh copied-plugin validation passed
• bun run check:python passed across all registered packages, including 154 darrow-tickets-github tests with 100% line and branch coverage
• bun test: 629 passed and 3 unrelated eval-runner tests failed; one timeout passed alone, one passed with --timeout 10000, and the remaining unchanged discovery-fixture assertion still fails alone because its named check is absent

Review notes

The highest-risk surface is the final-response handoff after a compound retrieval. The eval requires the exact ticket record first, verifies one bundled retrieval and the complete read-only GitHub protocol, applies only the separately authorized repository edit, and semantically checks the completion report. No shipped Bash mechanics were added; the new executable fixture mocks use Python.

Checklist

• I have read and followed CONTRIBUTING.md, including the contribution
  licensing terms.
• I added or updated the applicable invariant before implementation, or
  this change does not affect a capability invariant.
• I added or updated colocated evals, or this change does not affect skill
  behavior.
• I confirmed that each changed plugin remains self-contained, or this
  change does not affect plugin content.
• I ran bun run check:python, or this change does not affect registered
  Python packages or their repository quality infrastructure.

[BjRo]

Don't think this PR is good enough

[BjRo]

Superseded by the read-ticket/show-ticket capability split; restarting from main with the new contract.