hardening: verify privileged action state after command execution

[emi-ran]

Scope

Avoid reporting success only from shell/settings command return codes.

Required behavior

• NFC and Battery Saver actions poll authoritative platform state and fail on mismatch/unavailability
• Lock Screen reports verified completion where feasible, otherwise reports command accepted rather than completed
• Failed state readback does not create misleading success history/cooldown

Evidence

• NfcExecutor.kt:14-34
• PowerSaverExecutor.kt:44-69
• LockScreenExecutor.kt:19-30

Tests

Command returns success while state remains opposite; executor must not return state-enabled/state-disabled success.

Audit: 0a39f7e.