Expose named turret targeting actions

[sviyh]

Summary

• Refactor turret target cancellation and target commitment into named HaltTurret and CommitTarget methods.
• Preserve the existing gizmo behavior while exposing stable action boundaries for Multiplayer compatibility.

Motivation

The turret gizmo currently performs these state changes through inline UI logic and an anonymous targeting callback. Multiplayer compatibility therefore has to intercept lower-level UI or closure machinery to synchronize the actions. Named methods let the compatibility patch register the intended actions directly and remove brittle callback/transpiler handling.

Test plan

• Vehicle Framework Release build succeeds with no warnings or errors.
• Vanilla Vehicles Expanded rebuilds against the PR assemblies.
• Manual target commit: selecting a valid cell commits the target and starts the prefire timer without consuming ammunition.
• Manual target cancel: cancelling the targeter leaves the turret idle and preserves ammunition/reload state.
• Manual halt: halting an active target clears it and it remains cleared after subsequent ticks.
• Deployed build manually smoke-tested in game.