adventure: let an owner equip and unequip from their own page

The one adventure ask that carries intent back to the game box, built the
mischief way: no new network route, Pete records the equip/unequip and gogobee
polls it and files a verdict. The who page grows Equip / Take off buttons on the
owner's own worn and backpack panels, and a pending-changes strip that shows
'queued' until the verdict lands, never claiming a change it can't see.

The item handle is the inventory row id, sent only on wearable magic items, so a
non-zero id is also what gates the button. gogobee resolves the owner by
localpart, never a name.

internal/storage/detail.go

@@ -32,6 +32,11 @@ type PlayerDetail struct {
 // items can be Attuned — equipping moves the row out of gogobee's inventory
 // table entirely, so a backpack item's bond state isn't false, it's undefined.
 type ItemView struct {
+	// ID is the adventure_inventory row id, sent only for a backpack item that can
+	// be worn through the magic-item path — so a non-zero ID doubles as "this item
+	// has an Equip button." Worn items carry none: unequip keys on Slot. The id is
+	// the handle an equip order round-trips back to gogobee to name the item.
+	ID          int64  `json:"id,omitempty"`
 	Name        string `json:"name"`
 	Type        string `json:"type"`
 	Tier        int    `json:"tier"`