fix: disallow duplicate creation

Contributes to #25

src/routes/space/+page.svelte

@@ -12,6 +12,7 @@
     const { supabase } = $derived(data);
 
     let spaceImgs = $state<FileList>();
+    let uploading = $state(false);
     let studySpaceData = $state<Omit<Table<"study_spaces">, "id" | "created_at" | "updated_at">>({
         description: "",
         building_location: "",
@@ -73,7 +74,9 @@
 <form
     onsubmit={async (event) => {
         event.preventDefault();
+        uploading = true;
         await uploadStudySpace();
+        uploading = false;
     }}
 >
     <Images name="study-space-image" minHeight="16rem" bind:files={spaceImgs} required />
@@ -109,7 +112,8 @@
             disabled={(spaceImgs?.length || 0) === 0 ||
                 !studySpaceData.location ||
                 !studySpaceData.description ||
-                !studySpaceData.building_location}
+                !studySpaceData.building_location ||
+                uploading}
         >
             Share this study space!
         </Button>