fix: append filename to text input

Instead of clobbering the input text area just append the file path
at the end of the input.

This could be more clever by tracking where the cursor _was_ and inserting
the text there, but this seems better than just deleting the text.

Fixes block#1179

ui/desktop/src/components/Input.tsx

@@ -78,7 +78,7 @@ export default function Input({
   const handleFileSelect = async () => {
     const path = await window.electron.selectFileOrDirectory();
     if (path) {
-      setValue(path);
+      setValue(value + path);
       textAreaRef.current?.focus();
     }
   };