feat(03-01): add API endpoints for serving images

- Add GET /api/images/[id] for original images
- Add GET /api/images/[id]/thumbnail for thumbnails
- Both endpoints return 404 for missing images
- Immutable cache headers for CDN optimization

src/routes/api/images/[id]/+server.ts

@@ -0,0 +1,40 @@
+import { error } from '@sveltejs/kit';
+import { readFile } from 'node:fs/promises';
+import { imageRepository } from '$lib/server/db/repository';
+import { getOriginalPath } from '$lib/server/images/storage';
+import type { RequestHandler } from './$types';
+
+const MIME_TYPES: Record<string, string> = {
+	jpg: 'image/jpeg',
+	jpeg: 'image/jpeg',
+	png: 'image/png',
+	gif: 'image/gif',
+	webp: 'image/webp',
+	heic: 'image/heic',
+	heif: 'image/heif'
+};
+
+export const GET: RequestHandler = async ({ params }) => {
+	const { id } = params;
+
+	const image = imageRepository.getById(id);
+	if (!image) {
+		error(404, 'Image not found');
+	}
+
+	try {
+		const path = getOriginalPath(id, image.ext);
+		const buffer = await readFile(path);
+		const mimeType = MIME_TYPES[image.ext.toLowerCase()] || 'application/octet-stream';
+
+		return new Response(buffer, {
+			headers: {
+				'Content-Type': mimeType,
+				'Content-Length': buffer.length.toString(),
+				'Cache-Control': 'public, max-age=31536000, immutable'
+			}
+		});
+	} catch {
+		error(404, 'Image file not found');
+	}
+};

src/routes/api/images/[id]/thumbnail/+server.ts

@@ -0,0 +1,29 @@
+import { error } from '@sveltejs/kit';
+import { readFile } from 'node:fs/promises';
+import { imageRepository } from '$lib/server/db/repository';
+import { getThumbnailPath } from '$lib/server/images/storage';
+import type { RequestHandler } from './$types';
+
+export const GET: RequestHandler = async ({ params }) => {
+	const { id } = params;
+
+	const image = imageRepository.getById(id);
+	if (!image) {
+		error(404, 'Image not found');
+	}
+
+	try {
+		const path = getThumbnailPath(id);
+		const buffer = await readFile(path);
+
+		return new Response(buffer, {
+			headers: {
+				'Content-Type': 'image/jpeg',
+				'Content-Length': buffer.length.toString(),
+				'Cache-Control': 'public, max-age=31536000, immutable'
+			}
+		});
+	} catch {
+		error(404, 'Thumbnail not found');
+	}
+};