Bind the collapse's open state through wire:model and x-model

An application keeps a disclosure's state in a Livewire property
(`<x-collapse wire:model="fineTuning">`) or an Alpine one. Either binding
now works both ways: toggling the details writes the property, and the
property changing, in an action or in Alpine, opens or closes it.

`wire:model` is entangled as the dialog and sheets entangle theirs, and
taken off the element. The server renders `open` from the property, so
the first paint matches it. `x-model` binds through `x-modelable`, with
`open` as the first paint until Alpine starts. The state is named
`collapseOpen` so it never hides an `open` that a dialog in the slot reads
from a scope around it.

Without a binding the element has no Alpine and renders as before.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RHoXZSHc8gGpZjFmA5fPc2

resources/boost/skills/livewire-material-development/SKILL.md

@@ -427,6 +427,15 @@ A card or list item that opens something is a **row**: `data-list-row` on it and
 
 A disclosure on native `<details>`: `<x-collapse title="Advanced" icon="tune" open variant="filled">…</x-collapse>` (`variant` `plain` or `filled`; `heading` slot for rich titles). Keeps its state through a morph.
 
+Bind the open state to a boolean, both ways, with `wire:model` (any modifiers; `.live` sends each toggle at once) or `x-model`:
+
+```blade
+<x-collapse title="Fine-tuning" wire:model="fineTuning">…</x-collapse>
+<div x-data="{ advanced: false }"><x-collapse title="Advanced" x-model="advanced">…</x-collapse></div>
+```
+
+Toggling writes the property; changing the property (in an action or in Alpine) opens or closes it. With `wire:model` the server renders it open or closed as the property is, so there is no flash, and `open` is ignored; with `x-model`, `open` is only the first paint until Alpine starts. The bound state is `collapseOpen` in the `<details>` scope. Without a binding there is no Alpine on it.
+
 ### `<x-modal>`
 
 An M3 dialog on native `<dialog>`. Bind with `wire:model` to a flag or an id; closing (Escape, scrim, `close()`) writes back `false` or `null`. Without `wire:model` it uses `open` from the surrounding Alpine scope.