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/custom_section_templ.go

@@ -45,7 +45,7 @@ func CustomSectionBuilder(user User, libraries []LibraryData, errorMessage strin
 		var templ_7745c5c3_Var3 string
 		templ_7745c5c3_Var3, templ_7745c5c3_Err = templ.ResolveAttributeValue(templ.CSSClasses(templ_7745c5c3_Var2).String())
 		if templ_7745c5c3_Err != nil {
-			return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/custom_section.templ`, Line: 1, Col: 0}
+			return templ.Error{Err: templ_7745c5c3_Err, FileName: `custom_section.templ`, Line: 1, Col: 0}
 		}
 		_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ_7745c5c3_Var3)
 		if templ_7745c5c3_Err != nil {
@@ -87,7 +87,7 @@ func CustomSectionBuilder(user User, libraries []LibraryData, errorMessage strin
 			var templ_7745c5c3_Var4 string
 			templ_7745c5c3_Var4, templ_7745c5c3_Err = templ.ResolveAttributeValue(lib.ID)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/custom_section.templ`, Line: 74, Col: 31}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `custom_section.templ`, Line: 74, Col: 31}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ_7745c5c3_Var4)
 			if templ_7745c5c3_Err != nil {
@@ -100,7 +100,7 @@ func CustomSectionBuilder(user User, libraries []LibraryData, errorMessage strin
 			var templ_7745c5c3_Var5 string
 			templ_7745c5c3_Var5, templ_7745c5c3_Err = templ.JoinStringErrs(lib.Name)
 			if templ_7745c5c3_Err != nil {
-				return templ.Error{Err: templ_7745c5c3_Err, FileName: `templates/custom_section.templ`, Line: 74, Col: 44}
+				return templ.Error{Err: templ_7745c5c3_Err, FileName: `custom_section.templ`, Line: 74, Col: 44}
 			}
 			_, templ_7745c5c3_Err = templ_7745c5c3_Buffer.WriteString(templ.EscapeString(templ_7745c5c3_Var5))
 			if templ_7745c5c3_Err != nil {