Fix popup image manager async handling error

FIXED ERROR: 'files.filter is not a function' in popupImageManager.js

ISSUE:
- getLinkedImages() was calling electronAPI.readDirectory() without handling async/sync results
- readDirectory() can return Promise or Array depending on implementation
- Code assumed synchronous array result, causing TypeError when Promise returned

SOLUTION:
- Updated getLinkedImages() to handle both sync and async results from readDirectory()
- Made getLinkedImages(), getRandomPeriodicImage(), and showPeriodicPopup() async
- Added proper error handling for async directory reading
- Matches the pattern used successfully in game.js

RESULT: Popup images should now load properly from linked directories without errors

src/features/images/popupImageManager.js

@@ -71,8 +71,12 @@ class PopupImageManager {
         const { minInterval, maxInterval } = this.periodicSystem;
         const interval = Math.random() * (maxInterval - minInterval) + minInterval;
         
-        this.periodicSystem.interval = setTimeout(() => {
-            this.showPeriodicPopup();
+        this.periodicSystem.interval = setTimeout(async () => {
+            try {
+                await this.showPeriodicPopup();
+            } catch (error) {
+                console.error('Error showing periodic popup:', error);
+            }
             this.scheduleNextPeriodicPopup();
         }, interval);
 
@@ -82,12 +86,12 @@ class PopupImageManager {
     /**
      * Show a periodic random popup
      */
-    showPeriodicPopup() {
+    async showPeriodicPopup() {
         if (!this.periodicSystem.isActive) {
             return;
         }
 
-        const image = this.getRandomPeriodicImage();
+        const image = await this.getRandomPeriodicImage();
         if (!image) {
             console.log('⚠️ No images available for periodic popup');
             return;
@@ -99,9 +103,9 @@ class PopupImageManager {
     /**
      * Get random image for periodic popups (from linked directories and individual files)
      */
-    getRandomPeriodicImage() {
+    async getRandomPeriodicImage() {
         // Get images from the same sources as the main library
-        const allImages = this.getLinkedImages();
+        const allImages = await this.getLinkedImages();
 
         if (allImages.length === 0) {
             console.log('⚠️ No linked images available for popups');
@@ -150,7 +154,7 @@ class PopupImageManager {
     /**
      * Get all images from linked directories and individual files (same as main library)
      */
-    getLinkedImages() {
+    async getLinkedImages() {
         const allImages = [];
         
         try {
@@ -185,7 +189,24 @@ class PopupImageManager {
                 for (const dir of linkedDirs) {
                     try {
                         if (window.electronAPI.readDirectory) {
-                            const files = window.electronAPI.readDirectory(dir.path);
+                            const result = window.electronAPI.readDirectory(dir.path);
+                            
+                            let files = [];
+                            // Handle both sync and async results
+                            if (result && typeof result.then === 'function') {
+                                try {
+                                    files = await result;
+                                } catch (asyncError) {
+                                    console.error(`Error loading images from directory ${dir.path}:`, asyncError);
+                                    continue;
+                                }
+                            } else if (Array.isArray(result)) {
+                                files = result;
+                            } else {
+                                console.warn(`Unexpected result type from readDirectory for ${dir.path}:`, typeof result);
+                                continue;
+                            }
+                            
                             const imageFiles = files.filter(file => imageExtensions.test(file.name));
                             
                             imageFiles.forEach(file => {