Add server route to serve uploaded files in production

adapter-node only serves pre-built static assets, not files uploaded
at runtime. Added /uploads/[...path] catch-all route that reads from
static/uploads/ with proper MIME types and cache headers.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/routes/uploads/[...path]/+server.ts

@@ -0,0 +1,40 @@
+import type { RequestHandler } from './$types';
+import { readFile } from 'fs/promises';
+import { join, extname } from 'path';
+import { error } from '@sveltejs/kit';
+
+const MIME_TYPES: Record<string, string> = {
+	'.jpg': 'image/jpeg',
+	'.jpeg': 'image/jpeg',
+	'.png': 'image/png',
+	'.webp': 'image/webp',
+	'.gif': 'image/gif',
+	'.svg': 'image/svg+xml',
+	'.pdf': 'application/pdf',
+	'.txt': 'text/plain',
+	'.zip': 'application/zip'
+};
+
+export const GET: RequestHandler = async ({ params }) => {
+	const filePath = params.path;
+
+	// Prevent directory traversal
+	if (filePath.includes('..')) error(400, 'Invalid path');
+
+	const fullPath = join('static', 'uploads', filePath);
+
+	try {
+		const data = await readFile(fullPath);
+		const ext = extname(filePath).toLowerCase();
+		const contentType = MIME_TYPES[ext] ?? 'application/octet-stream';
+
+		return new Response(data, {
+			headers: {
+				'Content-Type': contentType,
+				'Cache-Control': 'public, max-age=86400'
+			}
+		});
+	} catch {
+		error(404, 'File not found');
+	}
+};