feat(frontend): add remove button to pending and submitted file cards

Lets users drop an uploaded file from the UI list before or after
conversion, without cancelling anything server-side.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/pages/HomePage.jsx

@@ -52,7 +52,7 @@ export function HomePage() {
         };
       })
     );
-    setPendingFiles(withTargets);
+    setPendingFiles((current) => [...current, ...withTargets]);
   }
 
   function updateTargetFormat(index, targetFormat) {
@@ -78,6 +78,14 @@ export function HomePage() {
     setPendingFiles((current) => current.map((item, i) => (i === index ? { ...item, iconSize } : item)));
   }
 
+  function removePendingFile(index) {
+    setPendingFiles((current) => current.filter((_, i) => i !== index));
+  }
+
+  function removeSubmittedJob(index) {
+    setSubmittedJobs((current) => current.filter((_, i) => i !== index));
+  }
+
   async function handleConvert() {
     const validItems = pendingFiles.filter((item) => item.targetFormat);
     const jobs = await uploadFiles(validItems);
@@ -114,6 +122,7 @@ export function HomePage() {
                     onTargetFormatChange={updateTargetFormat}
                     onQualityChange={updateQuality}
                     onIconSizeChange={updateIconSize}
+                    onRemove={removePendingFile}
                   />
                 ))}
               </ul>
@@ -132,6 +141,7 @@ export function HomePage() {
                   fileSize={job.size}
                   targetFormat={job.targetFormat}
                   jobId={job.id}
+                  onRemove={() => removeSubmittedJob(index)}
                 />
               ) : (
                 <FileCard
@@ -140,6 +150,7 @@ export function HomePage() {
                   fileSize={job.size}
                   targetFormat={job.targetFormat}
                   initialError={job.error}
+                  onRemove={() => removeSubmittedJob(index)}
                 />
               )
             )}