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/index_templ.go

@@ -37,7 +37,7 @@ func Index(loggedIn bool, registrationEnabled bool) 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>Bookhoard - Home</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\" x-data=\"index\" x-init=\"initIndexTheme(); checkAuthRedirect()\"><div class=\"absolute top-4 right-4 z-10\"><select id=\"theme-select\" @change=\"changeTheme\" class=\"input w-auto py-1.5 pr-8 text-sm cursor-pointer\" aria-label=\"Theme\"><optgroup label=\"Dark\">")
+		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>Bookhoard - Home</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 x-data=\"index\" x-init=\"initIndexTheme(); checkAuthRedirect()\"><div class=\"absolute top-4 right-4 z-10\"><select id=\"theme-select\" @change=\"changeTheme\" class=\"input w-auto py-1.5 pr-8 text-sm cursor-pointer\" aria-label=\"Theme\"><optgroup label=\"Dark\">")
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}
@@ -49,7 +49,7 @@ func Index(loggedIn bool, registrationEnabled bool) templ.Component {
 			var templ_7745c5c3_Var2 string
 			templ_7745c5c3_Var2, templ_7745c5c3_Err = templ.ResolveAttributeValue(opt.Name)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/index.templ`, Line: 26, Col: 31}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `index.templ`, Line: 26, Col: 31}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ_7745c5c3_Var2)
 			if templ_7745c5c3_Err != nil {
@@ -62,7 +62,7 @@ func Index(loggedIn bool, registrationEnabled bool) templ.Component {
 			var templ_7745c5c3_Var3 string
 			templ_7745c5c3_Var3, templ_7745c5c3_Err = templ.JoinStringErrs(opt.Label)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/index.templ`, Line: 26, Col: 45}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `index.templ`, Line: 26, Col: 45}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var3))
 			if templ_7745c5c3_Err != nil {
@@ -85,7 +85,7 @@ func Index(loggedIn bool, registrationEnabled bool) templ.Component {
 			var templ_7745c5c3_Var4 string
 			templ_7745c5c3_Var4, templ_7745c5c3_Err = templ.ResolveAttributeValue(opt.Name)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/index.templ`, Line: 31, Col: 31}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `index.templ`, Line: 31, Col: 31}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ_7745c5c3_Var4)
 			if templ_7745c5c3_Err != nil {
@@ -98,7 +98,7 @@ func Index(loggedIn bool, registrationEnabled bool) templ.Component {
 			var templ_7745c5c3_Var5 string
 			templ_7745c5c3_Var5, templ_7745c5c3_Err = templ.JoinStringErrs(opt.Label)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/index.templ`, Line: 31, Col: 45}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `index.templ`, Line: 31, Col: 45}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var5))
 			if templ_7745c5c3_Err != nil {