refactor: extract various constants

frontend/src/sidebar/Sidebar.tsx

@@ -32,6 +32,7 @@ import { useSidebarContext } from './SidebarContext';
 import { usePanelManager, usePanelResizeBindings } from '../app/PanelManagerContext';
 import type { StatusMessage } from '../hooks/documents/store/useDocumentsStore';
 import type { Identifier } from '../types/identifiers';
+import { THEME_MODE_LABELS, THEME_MODES } from '../constants/sidebar';
 
 interface CommunityLink {
   label: string;
@@ -260,13 +261,6 @@ const FolderNode: React.FC<FolderNodeProps> = ({
   );
 };
 
-const THEME_MODES = ['system', 'light', 'dark'];
-const THEME_MODE_LABELS = {
-  system: 'System',
-  light: 'Light',
-  dark: 'Dark',
-};
-
 interface FloatingMenuControls {
   isOpen: boolean;
   toggle: () => void;

frontend/src/sidebar/SidebarContext.tsx

@@ -6,6 +6,16 @@ import React, {
   useCallback,
   useEffect,
 } from 'react';
+import {
+  DARK_MODE_MEDIA_QUERY,
+  DEFAULT_NEUTRAL_CHROMA,
+  DEFAULT_NEUTRAL_CONTRAST,
+  DEFAULT_NEUTRAL_HUE,
+  DEFAULT_THEME_MODE,
+  SIDEBAR_COLLAPSE_STORAGE_KEY,
+  THEME_MODES,
+  THEME_STORAGE_KEY,
+} from '../constants/sidebar';
 
 interface SidebarContextValue {
   collapsed: boolean;
@@ -25,20 +35,10 @@ interface SidebarContextValue {
   themeModes: ThemeMode[];
 }
 
-type ThemeMode = 'system' | 'light' | 'dark';
-
-const SIDEBAR_COLLAPSE_STORAGE_KEY = 'papercrate_sidebar_collapsed';
+type ThemeMode = (typeof THEME_MODES)[number];
 
 const SidebarContext = createContext<SidebarContextValue | null>(null);
 
-const THEME_STORAGE_KEY = 'papercrate_theme_settings';
-const DEFAULT_NEUTRAL_HUE = 29;
-const DEFAULT_NEUTRAL_CHROMA = 0.44;
-const DEFAULT_NEUTRAL_CONTRAST = 0.56;
-const DEFAULT_THEME_MODE = 'system';
-const THEME_MODES = ['system', 'light', 'dark'];
-const DARK_MODE_MEDIA_QUERY = '(prefers-color-scheme: dark)';
-
 const loadInitialThemeSettings = () => {
   const defaults = {
     neutralHue: DEFAULT_NEUTRAL_HUE,