feat(image-import): add compressImage with canvas resize + JPEG re-encode

image-import.js

@@ -11,6 +11,57 @@ class ImageImporter {
         this.session = null;
         this.abortController = null;
     }
+
+    /**
+     * Resize image so the longest edge is <= 2048 px, re-encode as JPEG q=0.85.
+     * @param {File|Blob} file
+     * @returns {Promise<{blob: Blob, dataUrl: string, width: number, height: number}>}
+     */
+    async compressImage(file) {
+        const objUrl = URL.createObjectURL(file);
+        try {
+            const img = await new Promise((resolve, reject) => {
+                const i = new Image();
+                i.onload = () => resolve(i);
+                i.onerror = () => reject(new Error('Bild konnte nicht geladen werden'));
+                i.src = objUrl;
+            });
+
+            const longest = Math.max(img.width, img.height);
+            let newW = img.width;
+            let newH = img.height;
+            if (longest > 2048) {
+                const scale = 2048 / longest;
+                newW = Math.round(img.width * scale);
+                newH = Math.round(img.height * scale);
+            }
+
+            const canvas = document.createElement('canvas');
+            canvas.width = newW;
+            canvas.height = newH;
+            const ctx = canvas.getContext('2d');
+            ctx.drawImage(img, 0, 0, newW, newH);
+
+            const blob = await new Promise((resolve, reject) => {
+                canvas.toBlob(
+                    (b) => b ? resolve(b) : reject(new Error('toBlob fehlgeschlagen')),
+                    'image/jpeg',
+                    0.85
+                );
+            });
+
+            const dataUrl = await new Promise((resolve, reject) => {
+                const reader = new FileReader();
+                reader.onload = () => resolve(reader.result);
+                reader.onerror = () => reject(new Error('FileReader fehlgeschlagen'));
+                reader.readAsDataURL(blob);
+            });
+
+            return { blob, dataUrl, width: newW, height: newH };
+        } finally {
+            URL.revokeObjectURL(objUrl);
+        }
+    }
 }
 
 // Make available globally