fix(cua-driver): read macOS browser checkbox state

[injaneity]

problem

chrome 151 on macos exposes the exact chrome://inspect/#remote-debugging checkbox with a boolean axvalue. the adapter accepted only numeric 0/1, so existing-profile preparation refused with the exact remote-debugging checkbox had an unknown checked state before browser use or session cleanup could run.

scope

• add a shared macos ax binary-attribute reader that performs one native read
• accept native cfboolean values and exact numeric 0/1
• reject fractional, other numeric, string, missing, and unsupported values
• consume the normalized state for browser setup enable and rollback
• leave the existing truthy copy_bool_attr contract unchanged

duplicate and conflict check

no active pr already implements strict macos binary ax reads. #1757 changes batched tree reads in the same binding file but does not normalize boolean/numeric control state. #2064 added numeric axvalue support but does not cover binary reads.

validation

exact source: ad79aa13eb06a52c13cc21a0a87c8cc80d389dd1

• cargo test -p platform-macos ax::bindings::tests: 2 passed
• cargo test -p platform-macos browser::setup_ui::tests: 20 passed
• cargo fmt --all -- --check
• git diff --check
• source-installed cua driver 0.22.1 on macos 26.5.2 with chrome 151.0.7922.174:
  • the pre-fix live case reproduced unknown checked state
  • the fixed build completed existing-profile setup, page navigation, a dom click with fixture-state readback, end_session, devtools-listener shutdown, and the final native-tree assertion that allow remote debugging was absent
  • supporting diagnostic evidence: artifacts/cua-driver/macos-binary-checkbox-diagnostic-20260827T024423Z/
• version-matched supporting run with Google Chrome for Testing 151.0.7922.172 arm64 also completed setup, browser use, listener shutdown, and banner-absence cleanup; this is not the reporter’s official com.google.Chrome build because Google’s public stable endpoint no longer serves that patch

known gaps

• the supporting live run skipped the foreground, z-order, leaked-input, and cursor sentinels because this non-isolated host repeatedly stole chrome foreground during setup. those side-effect oracles remain unproven here.
• the complete canonical macos lume matrix remains required before this draft is made ready.