Fix image upload 500 in production: use UPLOAD_DIR env for absolute path

In production with adapter-node, the relative path 'static/uploads'
doesn't resolve correctly. Now uses UPLOAD_DIR env variable (absolute
path) for both saving and serving uploaded files.

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

src/lib/server/uploads.ts

@@ -1,9 +1,10 @@
 import { randomUUID } from 'crypto';
 import { writeFile, unlink, mkdir } from 'fs/promises';
-import { join, extname } from 'path';
+import { join, extname, resolve } from 'path';
 import sharp from 'sharp';
+import { env } from '$env/dynamic/private';
 
-const UPLOAD_BASE = 'static/uploads';
+const UPLOAD_BASE = resolve(env.UPLOAD_DIR || 'static/uploads');
 const THUMBNAIL_WIDTH = 300;
 
 const ALLOWED_IMAGE_TYPES = [
@@ -67,8 +68,9 @@ export async function saveDocument(file: File): Promise<{ filePath: string; orig
 
 export async function deleteFile(filePath: string): Promise<void> {
 	try {
-		// filePath is like /uploads/devices/xxx.jpg, need to prepend static/
-		const fullPath = join('static', filePath);
+		// filePath is like /uploads/devices/xxx.jpg — strip /uploads/ prefix and join with UPLOAD_BASE
+		const relativePath = filePath.replace(/^\/uploads\//, '');
+		const fullPath = join(UPLOAD_BASE, relativePath);
 		await unlink(fullPath);
 	} catch {
 		// File may already be deleted

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

@@ -1,7 +1,8 @@
 import type { RequestHandler } from './$types';
 import { readFile } from 'fs/promises';
-import { join, extname } from 'path';
+import { join, extname, resolve } from 'path';
 import { error } from '@sveltejs/kit';
+import { env } from '$env/dynamic/private';
 
 const MIME_TYPES: Record<string, string> = {
 	'.jpg': 'image/jpeg',
@@ -21,7 +22,8 @@ export const GET: RequestHandler = async ({ params }) => {
 	// Prevent directory traversal
 	if (filePath.includes('..')) error(400, 'Invalid path');
 
-	const fullPath = join('static', 'uploads', filePath);
+	const uploadBase = resolve(env.UPLOAD_DIR || 'static/uploads');
+	const fullPath = join(uploadBase, filePath);
 
 	try {
 		const data = await readFile(fullPath);