fix(cua-driver): exclude cursor overlay from foreground verification

[injaneity]

Refs #3681

Summary

Exclude the renderer-owned cursor window from macOS exact-window foreground verification. Only its registered native window ID is excluded; exact focus, foreground process, and genuine competing-window checks remain intact. Windows/Linux product behavior is unchanged by this PR.

Coverage

• Twenty consecutive exact activations during live peer-cursor overlap; fail on the first mismatch or premature producer expiry.
• A genuine competing window still causes the expected refusal, without moving the real pointer.
• Narrow report support for that foreground refusal; background side-effect requirements remain unchanged.

Current-candidate validation

Tested head: 2e16e3d84136c3fde6f7df85c2606f0eb634dc13, based on main 360e8ed62903437f3932517dc13c85ae79380373. The PR head and main base were rechecked after testing; neither changed. No final executable diff is unaccounted for.

432/432 desktop cases and 74/74 standalone-browser cases passed, including expected typed refusals. All reports show zero failed and zero skipped cases. Each full suite was run once; no behavioral retries, permission repairs, or weakened assertions.

Gate	Result	Evidence
macOS Lume desktop	163/163; both overlay/competitor regressions pass	Run 20260911T183239Z-55cc99ea, exit 0
Windows complete interactive matrix	138/138: shared 86, native 43, capture 9; installer/update smoke passes	Run 34633801973
Linux complete X11 matrix	131/131: shared 85, native 39, capture 7; installer smoke passes	Run 34633804375
macOS standalone Chrome	18/18	Same Lume run, --standalone-browser
Windows standalone Chrome/Edge	36/36	Run 34633806694
Linux X11 standalone Chrome	20/20	Run 34633806694
Ordinary PR CI	Green, including release metadata, contributor attribution, unit/compile, contract clients and docs	Current-head checks

The Windows native recording preflight finalized its video and passed before all 43 native cases executed. The previous native-lane evidence gap is closed for this candidate. #3713 remains an unresolved intermittent recorder failure; this passing candidate does not establish that it is fixed.

Native/browser runners enforced their strict evidence checks. On macOS, the standard daemon was restored and the run-owned worker was independently verified stopped and retained. No VM was deleted.

Environment and evidence limits

• macOS clone source: cua-driver-browser-baseline-20260908-chrome152, derived from a stopped fix(cua-driver): correct macos click delivery and recording evidence #2907 worker and retained feat(cua-driver): add target-scoped post-action rediscovery #3373 worker. Official Chrome 152.0.7977.83 signature/notarization was verified when the baseline was prepared. This is a worker-derived local baseline, not a certified immutable private release seed.
• Windows standalone isolated-launch cases verify the declared hosted-runner-token refusal; passing them does not claim support for protected isolated launch on that runner. Other browser cells and expected ambiguity refusals are recorded individually.
• Linux standalone tests use the documented disposable-browser no-sandbox environment. Linux evidence is X11, not certification of every Wayland compositor.
• Maintainer-local Lume evidence: /Users/administrator/.local/share/cua-lume-e2e/runs/20260911T183239Z-55cc99ea/. Downloaded hosted summaries/browser/native evidence: /Users/administrator/.local/share/cua-repros/3704/certification-2e16e3d84/. These local paths are not public download links; hosted run artifacts are linked above.

Current-candidate test gates are complete. Maintainer review/approval and merge remain outstanding; no merge or release was performed.

Historical evidence and recorder investigation (not current-candidate certification)

Previously tested candidate: 603d50e6bc76d5cb0538f827b536c4d21f47c6ae. No behavioral retries.

Gate	Result
macOS Lume	163/163 desktop + 18/18 installed-browser cases pass; strict recordings pass
Linux X11	All lanes pass: 131 behavior cases and installer smoke
Windows interactive	Shared (86), capture (9), and installer pass; native preflight blocked
Unit/compile checks	365 macOS tests pass (2 ignored); 95 testkit tests pass; native target compiles

Blocker

Tracking the pre-existing recorder failure in #3713, with isolated diagnostic work and results in #3714.

The Windows native preflight failed production FFmpeg recording shutdown before native behavior cases ran.

This failure predates the stack: main bd4c10020cd7cac07c0d19b0f53ba4b007fbcb15 had the same native preflight failure, followed by a successful native run at that identical SHA. The recorder backend, recording manager, preflight test, and FFmpeg setup script are byte-identical between that baseline and the failing candidate.

This establishes a pre-existing intermittent failure, not a new failure class introduced by these PRs. It does not establish a pure harness bug: stop_recording itself reports failure. The backend loses the distinction between nonzero exit and its three-second shutdown timeout, with empty stderr. Next diagnosis must retain exit status, shutdown timing, stdin-send errors, and force-kill usage. Existing evidence is preserved; no retry or weakened validation.

Evidence provenance

• Lume run: 20260910T152222Z-6ad05cea, exact candidate above, --standalone-browser, exit 0. Standard daemon restored; worker stopped and retained.
• Maintainer-local evidence: /Users/administrator/.local/share/cua-lume-e2e/runs/20260910T152222Z-6ad05cea.
• Baseline: cua-driver-browser-baseline-20260908-chrome152, derived from retained fix(cua-driver): correct macos click delivery and recording evidence #2907/feat(cua-driver): add target-scoped post-action rediscovery #3373 workers, not an immutable certified seed; official signed/notarized Chrome 152.0.7977.83.
• Original native TDD red: ab8a4353c9a432bde15148b91da23773ae58515d; minimal green: f3acfd8f5b091fd85360f917121e5c57ca72a31e. Earlier failed/setup evidence remains retained under its original SHA. Authors and commit messages were preserved across stacking.