fix: use $root for data attribute reads in Alpine interaction component

The extracted apCardInteraction component read data-mount-path,
data-csrf-token, and data-item-uid from this.$el inside interact(),
but $el may not be the x-data root when called from a child button
click. The old inline code used this.$root. Fixed by reading all
data attributes in init() and storing as component properties.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@rmdes/indiekit-endpoint-activitypub",
-  "version": "3.9.1",
+  "version": "3.9.2",
   "description": "ActivityPub federation endpoint for Indiekit via Fedify. Adds full fediverse support: actor, inbox, outbox, followers, following, syndication, and Mastodon migration.",
   "keywords": [
     "indiekit",