feat: use checksummed filenames for recipe images and clean up old files

Updated recipe image handling to use checksummed filenames for proper
cache busting. When uploading a new image during recipe edit, old image
files (both hashed and unhashed versions) are now properly deleted from
all directories (full, thumb, placeholder).

Changes:
- CardAdd.svelte: Use checksummed filename from upload response
- Edit page server: Add deleteRecipeImage() helper to remove old images
- Edit page server: Delete old images when new image is uploaded

src/lib/components/CardAdd.svelte

@@ -113,7 +113,7 @@ export async function show_local_image(){
 		}
 
 		const result = await response.json();
-		uploaded_image_filename = result.unhashedFilename;
+		uploaded_image_filename = result.filename;
 		upload_error = "";
 
 	} catch (error: any) {

src/routes/[recipeLang=recipeLang]/edit/[name]/+page.server.ts

@@ -4,7 +4,7 @@ import { Recipe } from '$models/Recipe';
 import { dbConnect } from '$utils/db';
 import { invalidateRecipeCaches } from '$lib/server/cache';
 import { IMAGE_DIR } from '$env/static/private';
-import { rename, access } from 'fs/promises';
+import { rename, access, unlink } from 'fs/promises';
 import { join } from 'path';
 import { constants } from 'fs';
 import {
@@ -14,6 +14,43 @@ import {
 	detectChangedFields
 } from '$utils/recipeFormHelpers';
 
+/**
+ * Delete recipe image files from all directories (full, thumb, placeholder)
+ * Handles both hashed and unhashed versions for backward compatibility
+ */
+async function deleteRecipeImage(filename: string): Promise<void> {
+	if (!filename) return;
+
+	const imageDirectories = ['full', 'thumb', 'placeholder'];
+
+	// Extract basename to handle both hashed and unhashed versions
+	const basename = filename
+		.replace(/\.[a-f0-9]{8}\.webp$/, '') // Remove hash if present
+		.replace(/\.webp$/, ''); // Remove extension
+
+	const unhashedFilename = basename + '.webp';
+
+	for (const dir of imageDirectories) {
+		// Delete hashed version (if it's the hashed filename that was passed in)
+		if (filename !== unhashedFilename) {
+			try {
+				await unlink(join(IMAGE_DIR, 'rezepte', dir, filename));
+				console.log(`Deleted hashed image: ${dir}/${filename}`);
+			} catch (err) {
+				console.warn(`Could not delete hashed image ${dir}/${filename}:`, err);
+			}
+		}
+
+		// Delete unhashed version
+		try {
+			await unlink(join(IMAGE_DIR, 'rezepte', dir, unhashedFilename));
+			console.log(`Deleted unhashed image: ${dir}/${unhashedFilename}`);
+		} catch (err) {
+			console.warn(`Could not delete unhashed image ${dir}/${unhashedFilename}:`, err);
+		}
+	}
+}
+
 export const load: PageServerLoad = async ({ fetch, params, locals}) => {
     // Edit is German-only - redirect to German version
     if (params.recipeLang === 'recipes') {
@@ -79,7 +116,11 @@ export const actions = {
 			const existingImagePath = formData.get('existing_image_path')?.toString();
 
 			if (uploadedImage) {
-				// New image uploaded - use it
+				// New image uploaded - delete old image files and use new one
+				if (existingImagePath && existingImagePath !== uploadedImage) {
+					await deleteRecipeImage(existingImagePath);
+				}
+
 				recipeData.images = [{
 					mediapath: uploadedImage,
 					alt: existingImagePath ? (recipeData.images?.[0]?.alt || '') : '',