fix(frontend): make fediverse login modals forms (fixes #97)

frontend/src/routes/auth/login/+page.svelte

@@ -34,7 +34,9 @@
     }
   });
 
-  const fediLogin = async () => {
+  const fediLogin = async (e: Event) => {
+    e.preventDefault();
+
     fediDisabled = true;
     try {
       const resp = await apiFetch<{ url: string }>(
@@ -71,12 +73,13 @@
         {/if}
       </ListGroup>
       <Modal header="Pick an instance" isOpen={modalOpen} toggle={toggleModal}>
+        <form on:submit={(e) => fediLogin(e)}>
           <ModalBody>
             <Input placeholder="Instance (e.g. mastodon.social)" bind:value={instance} />
             <p class="text-muted mt-2">
-            <Icon name="info-circle-fill" aria-label="Info" /> This should be the domain you use to access
+              <Icon name="info-circle-fill" aria-label="Info" /> This should be the domain you use to
-            posts. For example, if your username is <code>@timmie@mastodon.example</code>, but your
+              access posts. For example, if your username is <code>@timmie@mastodon.example</code>,
-            user <em>page</em> is at
+              but your user <em>page</em> is at
               <code>social.mastodon.example/timmie</code>, you should fill in
               <code>social.mastodon.example</code>.
             </p>
@@ -87,10 +90,11 @@
             {/if}
           </ModalBody>
           <ModalFooter>
-          <Button color="primary" disabled={fediDisabled || instance === ""} on:click={fediLogin}
+            <Button type="submit" color="primary" disabled={fediDisabled || instance === ""}
               >Log in</Button
             >
           </ModalFooter>
+        </form>
       </Modal>
       <p class="text-muted mt-2 mx-1">
         <Icon name="info-circle-fill" aria-hidden /> By signing in, you consent to pronouns.cc storing

frontend/src/routes/settings/auth/+page.svelte

@@ -44,7 +44,9 @@
   let googleUnlinkModalOpen = false;
   let toggleGoogleUnlinkModal = () => (googleUnlinkModalOpen = !googleUnlinkModalOpen);
 
-  const fediLogin = async () => {
+  const fediLogin = async (e: Event) => {
+    e.preventDefault();
+
     fediDisabled = true;
     try {
       const resp = await apiFetch<{ url: string }>(
@@ -205,6 +207,7 @@
       </div>
     {/if}
     <Modal header="Pick an instance" isOpen={fediLinkModalOpen} toggle={toggleFediLinkModal}>
+      <form on:submit={(e) => fediLogin(e)}>
         <ModalBody>
           <Input placeholder="Instance (e.g. mastodon.social)" bind:value={instance} />
           {#if error}
@@ -214,10 +217,11 @@
           {/if}
         </ModalBody>
         <ModalFooter>
-        <Button color="primary" disabled={fediDisabled || instance === ""} on:click={fediLogin}
+          <Button type="submit" color="primary" disabled={fediDisabled || instance === ""}
             >Log in</Button
           >
         </ModalFooter>
+      </form>
     </Modal>
 
     <Modal