feat: integrate ToastProvider and enhance theme management

- Added `ToastProvider` to `RootLayout` for improved user feedback on theme changes.
- Updated `ThemeProvider` to display toast notifications with theme names and icons upon theme changes.
- Refactored theme-related imports to streamline code and improve maintainability.
- Simplified background cycling logic in `useBackgroundCycle` to utilize centralized background definitions.
- Cleaned up unused background definitions in `BackgroundContext` for better clarity and performance.

src/app/layout.tsx

@@ -9,6 +9,7 @@ import { KeyboardShortcutsProvider } from "@/contexts/KeyboardShortcutsContext";
 import { userPreferencesService } from "@/services/core/user-preferences";
 import { KeyboardShortcuts } from "@/components/KeyboardShortcuts";
 import { GlobalKeyboardShortcuts } from "@/components/GlobalKeyboardShortcuts";
+import { ToastProvider } from "@/components/ui/Toast";
 import { AuthProvider } from "../components/AuthProvider";
 import { getServerSession } from 'next-auth';
 import { authOptions } from '@/lib/auth';
@@ -48,22 +49,24 @@ export default async function RootLayout({
         className={`${geistSans.variable} ${geistMono.variable} antialiased`}
       >
         <AuthProvider>
-          <ThemeProvider 
-            initialTheme={initialPreferences?.viewPreferences.theme || 'light'}
-            userPreferredTheme={initialPreferences?.viewPreferences.theme === 'light' ? 'dark' : initialPreferences?.viewPreferences.theme || 'light'}
-          >
-            <KeyboardShortcutsProvider>
-              <KeyboardShortcuts />
-              <JiraConfigProvider config={initialPreferences?.jiraConfig || { enabled: false }}>
-                <UserPreferencesProvider initialPreferences={initialPreferences}>
-                  <GlobalKeyboardShortcuts />
-                  <BackgroundProvider>
-                    {children}
-                  </BackgroundProvider>
-                </UserPreferencesProvider>
-              </JiraConfigProvider>
-            </KeyboardShortcutsProvider>
-          </ThemeProvider>
+          <ToastProvider>
+            <ThemeProvider 
+              initialTheme={initialPreferences?.viewPreferences.theme || 'light'}
+              userPreferredTheme={initialPreferences?.viewPreferences.theme === 'light' ? 'dark' : initialPreferences?.viewPreferences.theme || 'light'}
+            >
+              <KeyboardShortcutsProvider>
+                <KeyboardShortcuts />
+                <JiraConfigProvider config={initialPreferences?.jiraConfig || { enabled: false }}>
+                  <UserPreferencesProvider initialPreferences={initialPreferences}>
+                    <GlobalKeyboardShortcuts />
+                    <BackgroundProvider>
+                      {children}
+                    </BackgroundProvider>
+                  </UserPreferencesProvider>
+                </JiraConfigProvider>
+              </KeyboardShortcutsProvider>
+            </ThemeProvider>
+          </ToastProvider>
         </AuthProvider>
       </body>
     </html>