fix(cua-driver): unify native action scheduling

[injaneity]

What changed

Cua Driver used separate code to coordinate desktop actions and text entry. It also kept its own list of tools for each path, so a new tool could miss the right checks.

This pull request replaces that code with one small scheduler. It now:

• runs desktop actions one at a time;
• prevents two text operations from writing to the same process at once;
• applies the same text protection to type_text and type_text_chars; and
• keeps the action and the post-action window check from feat(cua-driver): add target-scoped post-action rediscovery #3373 together.

It also removes the old desktop lock, text-process set, custom cleanup guard, and duplicate tool list.

There are no browser or public API changes.

Refs #3373

Checks

Candidate 4e7bc5b20f567217034b4d0a50d542d67bd65eb0:

• formatting and diff checks pass;
• focused tests cover waiting, refusal, cancellation, cleanup, and tool selection; and
• all 23 reported CI checks pass.

This branch needs to be rebased onto the latest #3373 before merge.