feat: add AI-powered alt text generation for recipe images

- Implement local Ollama integration for bilingual (DE/EN) alt text generation
- Add image management UI to German edit page and English translation section
- Update Card and recipe detail pages to display alt text from images array
- Include GenerateAltTextButton component for manual alt text generation
- Add bulk processing admin page for batch alt text generation
- Optimize images to 1024x1024 before AI processing for 75% faster generation
- Store alt text in recipe.images[].alt and translations.en.images[].alt

src/routes/api/generate-alt-text/+server.ts

@@ -0,0 +1,94 @@
+import { json, error } from '@sveltejs/kit';
+import type { RequestHandler } from './$types';
+import { generateAltText, type RecipeContext } from '$lib/server/ai/alttext.js';
+import { checkOllamaHealth } from '$lib/server/ai/ollama.js';
+import { Recipe } from '$models/Recipe.js';
+
+export const POST: RequestHandler = async ({ request, locals }) => {
+	// Check authentication
+	const session = await locals.auth();
+	if (!session?.user) {
+		throw error(401, 'Unauthorized');
+	}
+
+	try {
+		const body = await request.json();
+		const { shortName, imageIndex, modelName } = body;
+
+		if (!shortName || imageIndex === undefined) {
+			throw error(400, 'Missing required fields: shortName and imageIndex');
+		}
+
+		// Check if Ollama is available
+		const isOllamaAvailable = await checkOllamaHealth();
+		if (!isOllamaAvailable) {
+			throw error(503, 'Ollama service is not available. Make sure Ollama is running.');
+		}
+
+		// Fetch recipe from database
+		const recipe = await Recipe.findOne({ short_name: shortName });
+		if (!recipe) {
+			throw error(404, 'Recipe not found');
+		}
+
+		// Validate image index
+		if (!recipe.images || !recipe.images[imageIndex]) {
+			throw error(404, 'Image not found at specified index');
+		}
+
+		const image = recipe.images[imageIndex];
+
+		// Prepare context for alt text generation
+		const context: RecipeContext = {
+			name: recipe.name,
+			category: recipe.category,
+			tags: recipe.tags,
+		};
+
+		// Generate alt text in both languages
+		const altTextResult = await generateAltText(
+			image.mediapath,
+			context,
+			modelName || 'gemma3:latest'
+		);
+
+		// Update recipe in database
+		recipe.images[imageIndex].alt = altTextResult.de;
+
+		// Ensure translations.en.images array exists and has the right length
+		if (!recipe.translations) {
+			recipe.translations = { en: { images: [] } };
+		}
+		if (!recipe.translations.en) {
+			recipe.translations.en = { images: [] };
+		}
+		if (!recipe.translations.en.images) {
+			recipe.translations.en.images = [];
+		}
+
+		// Ensure the en.images array has entries for all images
+		while (recipe.translations.en.images.length <= imageIndex) {
+			recipe.translations.en.images.push({ alt: '', caption: '' });
+		}
+
+		// Update English alt text
+		recipe.translations.en.images[imageIndex].alt = altTextResult.en;
+
+		// Save to database
+		await recipe.save();
+
+		return json({
+			success: true,
+			altText: altTextResult,
+			message: 'Alt text generated and saved successfully',
+		});
+	} catch (err) {
+		console.error('Error generating alt text:', err);
+
+		if (err instanceof Error && 'status' in err) {
+			throw err; // Re-throw SvelteKit errors
+		}
+
+		throw error(500, err instanceof Error ? err.message : 'Failed to generate alt text');
+	}
+};