fix(admin): un-dead the archived page's purge and delete buttons

Two independent dead-ends, confirmed on prod's /admin/archived
(2026-10): Purge All rendered but clicking it did nothing at all, and
per-row Delete never even showed its confirm dialog.

Purge All is Alpine-bound (@click="purgeArchivedItems()"), but this
page's <body> lacked x-data="admin" — the only admin page without it.
Alpine evaluates directives only inside an x-data tree, so the
attribute was inert: the admin component (and its method, registered
in admin.ts) never instantiated here. The body now carries
x-data="admin", matching admin.templ and admin_library.templ.

Per-item Delete was a second, subtler dead-end: admin.ts's API helpers
guard with `if (!token) return;` BEFORE the confirm dialog, and the
reporting session had no localStorage token — SSR pages run on the
cookie session, so the web UI works while every Bearer-
authenticated admin action (purge, delete, restore, merge, scan-all,
cancel-scan) silently no-ops with zero feedback. Those guards now go
through requireToken, which toasts "Session expired — sign out and
back in, then retry" when the token is absent. The two passive
page-load probes (loadWatchStatus, checkActiveScans) deliberately keep
the silent return: a toast there would fire on every visit.

Pinned by TestAdminArchivedPageHasAlpineScope: renders the page and
asserts the body scope and the action buttons coexist in one render.

After deploy: hard-refresh prod, click Purge All (confirm appears);
if the token toast fires on any admin action, log out and back in once
to stash a fresh API token.

templates/admin_archived.templ

@@ -10,7 +10,7 @@ templ AdminArchived(user User, items []ArchivedItem, retentionDays int) {
 			<link href="/static/style.css" rel="stylesheet"/>
 			<link rel="icon" type="image/svg+xml" href="/static/favicon.svg"/>
 		</head>
-		<body class={ "theme-" + user.Theme }>
+		<body x-data="admin" class={ "theme-" + user.Theme }>
 			@Header(user, "/admin/archived")
 			<main class="p-8">
 				<div class="max-w-5xl">