* feat(harness): subagent receipt citation verification
- add receipt citation verification core
- harvest subagent tool receipts at terminal status
- transport subagent receipts and citation verdict via status contract
- verify subagent report citations at task write-back
- render citation verdicts in the delegation ledger
* fix(gateway): strip forged receipt verdicts from the delegations channel
normalize_input() and the checkpoint-state mutation sanitizer only
stripped server-owned metadata from message-shaped values, so an
external caller could submit a delegation entry carrying a forged
receipt_verdict that render_delegation_ledger would present as
runtime-owned execution evidence. Strip receipt_verdict from
caller-supplied delegation entries on both the run-creation and
thread-state mutation paths, with regression coverage for each.
* fix(harness): close silent-pass gaps in the zero-citation heuristic
The action-claim detector missed the most common completion verbs
(fixed/added/tested/changed/...) and had no CJK coverage at all, so
reports like 'I fixed the bug and added tests.' or '我已经创建了文件并运行了测试。'
were treated as claim-free: citation_resolved=True with no ledger
warning. Broaden the verb lists and add a language-independent safety
net: when the run harvested receipts and a nontrivial (>=240 char)
report cites none of them, flag it UNVERIFIED. Short claim-free
confirmations remain a vacuous pass.
