feat: support BYO backup recipient

[k9ert]

Summary

• add --it-recipient for greenfield backup/escrow recipient selection while keeping the bundled Blink key as default
• respect existing secrets/.gpg-id, log recipients, and warn on missing/malformed/single-recipient stores
• make doctor key-agnostic with >=2 recipient enforcement and recipient key presence checks
• document repo-scoped pass trust behavior and bump version to 1.9.0

Tests

• PYENV_VERSION=3.11.13 PYTHONPATH=src GNUPGHOME=/tmp/argit-unit-gnupg python -m pytest -p no:cacheprovider tests/unit
• PYENV_VERSION=3.11.13 PYTHONPATH=src python -m pytest -p no:cacheprovider tests/integration/test_setup_integration.py tests/integration/test_roundtrip.py::test_byo_recipient_roundtrip_restores_plaintext

Note: ruff is unavailable in the local Python 3.11 environment (No module named ruff).

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[blink-claw-bot]

HIGH

• None.

MEDIUM

• None.

LOW

• None.

Reviewed the BYO backup recipient flow, the key-agnostic doctor changes, pass trust-model handling, the new argit info command, and the bundled argit-backup skill/docs. The implementation preserves existing .gpg-id authority, keeps greenfield setup explicit, and has coverage for the main recipient/roundtrip paths.

Verified locally:

• PYTHONPATH=src GNUPGHOME=/tmp/argit-unit-gnupg python3 -m pytest -p no:cacheprovider tests/unit → 380 passed
• PYTHONPATH=src:/home/openclaw/.local/lib/python3.10/site-packages python3 -m pytest -p no:cacheprovider tests/integration/test_setup_integration.py tests/integration/test_roundtrip.py::test_byo_recipient_roundtrip_restores_plaintext → 8 passed
• PYTHONPATH=src python3 -m argit.cli info --json | python3 -m json.tool → OK

🤖 Review by GPT-5 Codex via Blink-Claw-Bot