ui: fix admin/docs theme flash + persist sidebar open/closed state

Theme flash (admin pages, docs, stats, progress — anywhere SSR'd):
the JWT middlewares built the context user WITHOUT the Theme column,
so every page rendering theme-{user.Theme} from c.Get("user") painted
an empty class (:root tokyo-night default) and only settled on the real
theme after initializeTheme -> loadUserTheme round-tripped the server.
Both middlewares now carry liveUser.Theme into the context user;
verified live: /admin /stats /progress /docs /docs-deep /dashboard
/collections all SSR theme-hackerman.

Defense in depth for the same bug: loadTheme() no longer re-applies
localStorage over a server-rendered body theme (applyTheme records even
the default, so any signed-out visit baked tokyo-night into localStorage
and every signed-in page flipped to it post-paint). Public auth/landing
bodies dropped their hardcoded theme classes so ThemeFlashGuard's
pre-paint html class actually governs them; docs theme <select> now
syncs from the body class and re-syncs after the profile fetch.

Sidebar state (the unpleasant part): the app sidebar's openPanel was
reinitialized from the pathname on every load; it now restores from
localStorage ('sidebar-open-panel') with the pathname default as
fallback and -persists every toggle. Docs sidebar sections/groups
carry data-key attributes and toggleCollapsible persists collapsed
state per key ('docs-nav-state'); restoreDocsNav() applies it at init —
server-rendered defaults still govern first visit.

make test green; rendering ownership OK (no new inline scripts); 146
vitests pass; live-verified SSR classes on 7 pages.

templates/setup_templ.go

@@ -39,7 +39,7 @@ func Setup(libraryTypes []database.LibraryTypes) templ.Component {
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}
-		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 2, "<meta charset=\"UTF-8\"><meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\"><title>Setup - Bookhoard</title><script src=\"/static/htmx.min.js\"></script><script type=\"module\" src=\"/static/main.js\"></script><link href=\"/static/style.css\" rel=\"stylesheet\"><link rel=\"icon\" type=\"image/svg+xml\" href=\"/static/favicon.svg\"></head><body class=\"theme-tokyo-night min-h-screen\" x-data=\"setupWizard\" x-init=\"initSetup()\"><div class=\"mx-auto container px-4 py-8 max-w-2xl\"><div class=\"text-center mb-8\"><span class=\"inline-grid place-items-center h-14 w-14 rounded-2xl mx-auto mb-4\" style=\"background-color: var(--accent-muted); color: var(--accent);\">")
+		templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 2, "<meta charset=\"UTF-8\"><meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\"><title>Setup - Bookhoard</title><script src=\"/static/htmx.min.js\"></script><script type=\"module\" src=\"/static/main.js\"></script><link href=\"/static/style.css\" rel=\"stylesheet\"><link rel=\"icon\" type=\"image/svg+xml\" href=\"/static/favicon.svg\"></head><body class=\"min-h-screen\" x-data=\"setupWizard\" x-init=\"initSetup()\"><div class=\"mx-auto container px-4 py-8 max-w-2xl\"><div class=\"text-center mb-8\"><span class=\"inline-grid place-items-center h-14 w-14 rounded-2xl mx-auto mb-4\" style=\"background-color: var(--accent-muted); color: var(--accent);\">")
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}