fix(cua-driver): explain permanent scope recovery

[f-trycua]

Summary

• make the auto-session window_scope_disabled error state that desktop escalation is permanent for that session
• direct callers to end_session, then start_session with a new session id
• align the generated contract and shipped Cua Driver skill without changing one-way containment semantics

Testing

• cargo test --locked -p cua-driver-core capture_scope::tests::
• cargo test --locked -p cua-driver --test session_capture_scope_test
• cargo test --locked -p cua-driver-contract
• cargo run --locked -p cua-driver-contract --bin cua-contract-gen -- all --check
• cargo fmt --all -- --check

Fixes #2844