Fix: $watch and x-modelable can fire after being unwatched/released

[MaxencePaulin]

Summary

• watch() and entangle() build their effect with the default effect(), not elementBoundEffect(el). Unlike directive effects (x-show, x-text, etc.), their job is never tracked in an element's _x_effects. That means cleanupElement()'s el._x_effects?.forEach(dequeueJob) sweep never reaches them: a value change that queues their effect right before the watcher is torn down can leave a stale job in the scheduler that still runs afterward.
• While tracking this down, I noticed Alpine.entangle() has the exact same problem, whether it's reached through x-modelable or Livewire's $wire.$entangle, so this PR fixes both.
• Fixed by dequeuing the effect explicitly in the function each one returns, right before releasing it. No public API change, so existing consumers (Livewire's $wire.$watch included) get the fix for free.

Alternatives considered

• Override release globally to always dequeue. I haven't measured the performance impact or the scope of this change.
• Check whether the effect is still active at the moment a queued job runs, instead of dequeuing. I don't know if that's feasible, and haven't measured any performance cost either.
• Fix this only in $watch and x-modelable, not in Alpine.watch/Alpine.entangle themselves. That would leave direct consumers of the primitives (like Livewire) needing to adapt their own code to benefit from the fix, which I'd rather avoid.

Test plan

• tests/cypress/integration/magics/$watch.spec.js, $watch does not fire for a change made after its element is removed
• tests/cypress/integration/directives/x-modelable.spec.js, x-modelable does not resync for a change made after its element is removed
• npm run test && npm run vitest (unaffected, still green)

Fixes #4902