fix: percent-encode X-File-Results header to support non-ASCII filenames

The X-File-Results header contained raw JSON with non-ASCII characters
from filenames (Chinese, Japanese, etc.), violating RFC 7230. Node.js
threw ERR_INVALID_CHAR on writeHead(). Fixed by wrapping the JSON in
encodeURIComponent() on the backend and decodeURIComponent() on the
frontend, ensuring only ASCII goes into the header while preserving
the original filenames after decoding.

Closes #133

apps/api/src/routes/batch.ts

@@ -262,7 +262,7 @@ export async function registerBatchRoutes(app: FastifyInstance): Promise<void> {
         "Content-Disposition": `attachment; filename="batch-${toolId}-${jobId.slice(0, 8)}.zip"`,
         "Transfer-Encoding": "chunked",
         "X-Job-Id": jobId,
-        "X-File-Results": JSON.stringify(fileResultsMap),
+        "X-File-Results": encodeURIComponent(JSON.stringify(fileResultsMap)),
       });
 
       const archive = archiver("zip", { zlib: { level: 5 } });

apps/api/src/routes/pipeline.ts

@@ -731,7 +731,7 @@ export async function registerPipelineRoutes(app: FastifyInstance): Promise<void
       "Content-Disposition": `attachment; filename="pipeline-batch-${jobId.slice(0, 8)}.zip"`,
       "Transfer-Encoding": "chunked",
       "X-Job-Id": jobId,
-      "X-File-Results": JSON.stringify(fileResultsMap),
+      "X-File-Results": encodeURIComponent(JSON.stringify(fileResultsMap)),
     });
 
     const archive = archiver("zip", { zlib: { level: 5 } });

apps/api/src/routes/tools/svg-to-raster.ts

@@ -300,7 +300,7 @@ export function registerSvgToRaster(app: FastifyInstance) {
       "Content-Disposition": `attachment; filename="batch-svg-to-raster-${jobId.slice(0, 8)}.zip"`,
       "Transfer-Encoding": "chunked",
       "X-Job-Id": jobId,
-      "X-File-Results": JSON.stringify(fileResultsMap),
+      "X-File-Results": encodeURIComponent(JSON.stringify(fileResultsMap)),
     });
 
     const archive = archiver("zip", { zlib: { level: 5 } });

apps/web/src/hooks/use-pipeline-processor.ts

@@ -330,7 +330,9 @@ export function usePipelineProcessor() {
         const entries = useFileStore.getState().entries;
         let fileResults: Record<string, string> = {};
         try {
-          fileResults = JSON.parse(response.headers.get("X-File-Results") ?? "{}");
+          fileResults = JSON.parse(
+            decodeURIComponent(response.headers.get("X-File-Results") ?? "%7B%7D"),
+          );
         } catch {
           // Malformed header - fall back to empty mapping, all entries marked failed
         }

apps/web/src/hooks/use-tool-processor.ts

@@ -384,7 +384,9 @@ export function useToolProcessor(toolId: string) {
         const entries = useFileStore.getState().entries;
         let fileResults: Record<string, string> = {};
         try {
-          fileResults = JSON.parse(response.headers.get("X-File-Results") ?? "{}");
+          fileResults = JSON.parse(
+            decodeURIComponent(response.headers.get("X-File-Results") ?? "%7B%7D"),
+          );
         } catch {
           // Malformed header - fall back to empty mapping, all entries marked failed
         }