fix(runtime): tolerate Windows receipt fsync limits

[liomilet4-png]

Summary

Fixes a remaining Windows receipt-store durability failure on the current main branch.

• route durable temporary-file sync through a helper that keeps normal errors strict
• tolerate Windows sync_all raw OS error 87 after the receipt file has been written and flushed
• make receipt-directory sync a no-op on Windows, while keeping non-Windows File::open(path)?.sync_all() behavior unchanged

This is intentionally a focused one-file PR. Existing broader receipt/skill PRs such as #201 are conflict-heavy and do not cover the temp-file sync_all error path on current main.

Validation

• cargo fmt -p runx-runtime -- --check
  • passed
• git diff --check -- crates/runx-runtime/src/receipts/store.rs
  • passed
• cargo test -p runx-runtime receipt_store -- --nocapture
  • passed: receipt_store 26 passed, 0 failed

Scope

The change is limited to local receipt-store durability sync behavior. It does not change receipt IDs, receipt file naming, signatures, verification policy, harness authority, or any public schema.

[liomilet4-png]

Thanks for taking a look. The PR workflows currently appear to be waiting for maintainer approval (ci and secret-scan are both action_required on the PR commit).

Could a maintainer approve the workflows so the branch can run CI?

The change is intentionally limited to the Windows receipt-store fsync/directory-sync behavior, with local validation passing:

• cargo fmt -p runx-runtime -- --check
• git diff --check -- crates/runx-runtime/src/receipts/store.rs
• cargo test -p runx-runtime receipt_store -- --nocapture