feat: forward terminate from the kit to the Rokt launcher

[jamesnrokt]

Summary

Adds RoktKit.terminate(), which forwards to launcher.terminate() on the Rokt Web SDK.

This is the kit half of a supported teardown path for window.mParticle.Rokt.terminate(). The core SDK half is in mParticle/mparticle-web-sdk#1328; that PR's RoktManager.terminate() delegates to this method. This PR should merge and release first — the manager guards the call with isFunction, so until a kit carrying this change is on the page, mParticle.Rokt.terminate() logs that the attached kit version does not support it.

Partners currently tear down placements with the undocumented window.Rokt.currentLauncher?.terminate(). This makes the same call reachable through the documented interface.

Behaviour

• Ready: returns launcher.terminate() directly, so callers can await the teardown. The launcher's own terminate races an internal 500ms timeout and never rejects.
• Not ready: logs Rokt Kit: Not initialized and resolves. Teardown is idempotent — with no launcher there is nothing to tear down.

The launcher reference is deliberately left in place

terminate() does not null out this.launcher or window.Rokt.currentLauncher. The Rokt Web SDK memoizes a single launcher per page (createLauncher returns the cached promise once fulfilled), so clearing our references could not buy the caller a fresh launcher — it would only flip isKitReady() to false and leave every later selectPlacements call queued forever with no drain path.

Leaving state untouched makes this exactly equivalent to the window.Rokt.currentLauncher.terminate() call partners already make, just reachable through a supported API. There is a test pinning this.

Testing Plan

npm run lint, npm run build, npm run test all pass — 313/313 Vitest tests, including 6 new #terminate cases covering:

• launcher.terminate is called when fully initialized
• the launcher's promise is returned and awaitable
• resolves as a no-op, without touching the launcher, when uninitialized
• resolves as a no-op when initialized but the launcher is missing
• launcher references survive teardown so the kit stays ready
• end-to-end through init() + attachKit in test mode

All 6 fail against main without the source change.

Suggested manual check

On a page with a rendered placement, await window.Rokt.currentLauncher.terminate() and await window.mParticle.Rokt.terminate() (once mParticle/mparticle-web-sdk#1328 is also deployed) should be indistinguishable.

🤖 Generated with Claude Code

[mattbodle]

Typically createLauncher can be called again after terminate, usually for SPAs.
Can this create another launcher instance in that flow and continue? (given the launcher reference is maintained)
Create a test to capture this scenario