Fix action approach walks being interrupted or shortened

[taylorszz]

Summary

Fixes scripted action approach walks being incorrectly interrupted, shortened, or path-skipped before the associated NVC action begins.

Covers Issue #51

Changes

• Track the action approach phase so pre-NVC walks are not treated as active NVC actions.
• Prevent trigger regions and SkipToView from interrupting walks during an action approach.
• Only allow trigger-shortening while an actual NVC action script is running, not during manual/pre-action interruptions.
• Prevent frustum path skipping from incorrectly shortening or bypassing action approach paths.
• Update GKActor walk-to-animation handling so the approach walk is completed before starting the associated animation/action.

Result

Action approach walks now complete as intended without being prematurely shortened or interrupted by trigger handling, SkipToView, or frustum path optimization, while preserving the existing interruption behavior once the actual NVC action has started.