feat(frontend): POST for images

caddy/Caddyfile.example

@@ -26,6 +26,9 @@
     }
 
     handle {
+        request_body {
+            max_size 50MB
+        }
         reverse_proxy stealth-ai-relay-frontend:3000
     }
 }

frontend/src/routes/[mnemonic]/+server.ts

@@ -37,11 +37,21 @@ export const POST: RequestHandler = async ({ params, request, locals }) => {
 
 	if (rawContentType.includes('multipart/form-data')) {
 		const formData = await request.formData();
-		console.log('[POST /{mnemonic}] formData keys:', [...formData.keys()]);
+		const keys = [...formData.keys()];
+		console.log('[POST /{mnemonic}] formData keys:', keys);
 
-		const file = formData.get('file') || formData.get('image') || formData.values().next().value;
-		if (!(file instanceof File)) {
-			throw error(400, 'No file found in form data');
+		let file: File | null = null;
+		for (const key of ['file', 'image', 'photo', 'upload', 'attachment', ...keys]) {
+			const value = formData.get(key);
+			if (value instanceof File) {
+				file = value;
+				console.log('[POST /{mnemonic}] found file in field:', key);
+				break;
+			}
+		}
+
+		if (!file) {
+			throw error(400, `No file found in form data. Keys: ${keys.join(', ')}`);
 		}
 
 		const buffer = await file.arrayBuffer();
@@ -50,6 +60,8 @@ export const POST: RequestHandler = async ({ params, request, locals }) => {
 		mediaType = detectImageType(bytes) || file.type || 'image/jpeg';
 
 		console.log('[POST /{mnemonic}] file:', file.name, file.type, 'size:', buffer.byteLength);
+	} else if (rawContentType.includes('application/x-www-form-urlencoded')) {
+		throw error(400, 'Use Form with File field, not URL-encoded form');
 	} else {
 		const buffer = await request.arrayBuffer();
 		const bytes = new Uint8Array(buffer);