feat: enhance background image handling with cache-busting

- Added a cache-busting query parameter to the background image URL to ensure the browser reloads the image when updated.
- Updated the AppState to include an optional imageVersion property for managing image updates.
- Modified the BoardBackgroundModal and BoardView components to utilize the new imageVersion for dynamic image loading.

apps/app/src/store/app-store.ts

@@ -372,6 +372,7 @@ export interface AppState {
     string,
     {
       imagePath: string | null; // Path to background image in .automaker directory
+      imageVersion?: number; // Timestamp to bust browser cache when image is updated
       cardOpacity: number; // Opacity of cards (0-100)
       columnOpacity: number; // Opacity of columns (0-100)
       columnBorderEnabled: boolean; // Whether to show column borders
@@ -1316,6 +1317,8 @@ export const useAppStore = create<AppState & AppActions>()(
             [projectPath]: {
               ...existing,
               imagePath,
+              // Update imageVersion timestamp to bust browser cache when image changes
+              imageVersion: imagePath ? Date.now() : undefined,
             },
           },
         });
@@ -1516,6 +1519,7 @@ export const useAppStore = create<AppState & AppActions>()(
             [projectPath]: {
               ...existing,
               imagePath: null, // Only clear the image, preserve other settings
+              imageVersion: undefined, // Clear version when clearing image
             },
           },
         });