Fix published remote Action SHA propagation

[avoroncov971-maker]

Allowlist

• action.yml
• action/run.sh
• tests/test_action.py

The remote Action failed before invoking the CLI. Pass action context using PROOF_CHECK_ACTION_REF and PROOF_CHECK_ACTION_REPOSITORY; retain full-SHA validation and local-workspace refusal. Default GITHUB_* variables are runner-owned: https://docs.github.com/en/actions/reference/workflows-and-actions/variables

Owner authorized this separate repair in chat. Regression covers remote action outside workspace with empty runner-owned variables, plus refusal when explicit remote pin is absent. No contract changes.

Repair SHA: 201bac98ac95bd173e6132510a3de3f7af064610.
Local: python3 -m pytest -q -> 358 passed, exit 0 (67.82s); focused Action tests 16 passed; git diff --check exit 0.
Remote consumer: PR #8 head a18dc779b3da64b6aab84f528fea0fbb2bc42639 uses the repair by full SHA. All three hosted checks success.
Check: https://github.com/deedseal/proof-check/actions/runs/34180465267/job/101918337921
CLI: PASS, one changed path, exact consumer head; offline proof-check verify -> VERIFIED, exit 0.
Receipt artifact: 10038713415. Offline bundle: 10038715749.
This verifies remote consumption, not merge enforcement; protection remains a separate Owner act.

Original failing run: https://github.com/deedseal/proof-check/actions/runs/34180270668/job/101917770789
Draft for independent review and Owner merge; no release tag moved.

[avoroncov971-maker]

@claude Please perform a READ_ONLY_ANALYSIS review of this exact PR head:

repository: deedseal/proof-check
PR: #9
head: 201bac9
base: f26daae

Review only the three allowlisted files. Independently verify the failure mechanism from the original remote-consumer run, the environment-variable repair, full-SHA refusal behavior, receipt/head binding, and the successful remote-consumer evidence on PR #8. Do not edit files, push, approve, mark Ready, merge, release, or change repository settings.

Return one exact-head disposition in the PR conversation: PASS, BLOCKED, or INDETERMINATE, with any blocking finding tied to a reproducible counterexample.