Refactor image utilities and cache to separate modules

Moved image data validation, conversion, mask application, and preparation functions from Canvas_view.js to a new ImageUtils.js module. Extracted the image cache logic into a new ImageCache.js class. Updated Canvas_view.js to use the new modules and refactored relevant imports and usage.

js/ImageCache.js

@@ -0,0 +1,25 @@
+export class ImageCache {
+    constructor() {
+        this.cache = new Map();
+    }
+
+    set(key, imageData) {
+        console.log("Caching image data for key:", key);
+        this.cache.set(key, imageData);
+    }
+
+    get(key) {
+        const data = this.cache.get(key);
+        console.log("Retrieved cached data for key:", key, !!data);
+        return data;
+    }
+
+    has(key) {
+        return this.cache.has(key);
+    }
+
+    clear() {
+        console.log("Clearing image cache");
+        this.cache.clear();
+    }
+}