Send AI POSTs urlencoded instead of multipart

A multipart POST to this endpoint hangs: no status code is ever returned, and
the request never reaches PHP — no CSRF termination, no fatal, no entry log —
despite leaving the browser with a valid token and a correct body. Every POST
on this host that demonstrably works, including Unraid's own, is
x-www-form-urlencoded. Same fields and same $_POST server-side.

Plugin/unraid/pages/ai.php

@@ -436,15 +436,26 @@ if (is_dir('/var/log/varaverk')) {
     // installed elsewhere on the page — would escape the promise chain entirely and leave the
     // pending indicator up forever with nothing logged anywhere. A hang is the one failure
     // that tells you nothing, so every path below has to end in a visible message.
+    // URLSearchParams, not FormData. FormData sends multipart/form-data, and a multipart POST
+    // to this endpoint hangs with no status code ever returned — the request leaves the browser
+    // with a valid token and correct body, and never reaches PHP: no CSRF termination, no
+    // fatal, no entry log. Every other POST on this host that demonstrably works, including
+    // Unraid's own, is application/x-www-form-urlencoded. Same fields, same $_POST on the
+    // server; only the encoding changes.
     let res;
     try {
-      const fd = new FormData();
-      fd.append('action', 'ask');
-      fd.append('question', q);
-      fd.append('history', JSON.stringify(history.slice(-MAXTURN * 2)));
-      fd.append('kind', $('vv-ai-kind').value);
-      fd.append('think', $('vv-ai-think').checked ? '1' : '0');
-      res = fetch(API, { method: 'POST', body: fd });
+      const body = new URLSearchParams({
+        action:   'ask',
+        question: q,
+        history:  JSON.stringify(history.slice(-MAXTURN * 2)),
+        kind:     $('vv-ai-kind').value,
+        think:    $('vv-ai-think').checked ? '1' : '0',
+      });
+      res = fetch(API, {
+        method:  'POST',
+        headers: { 'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8' },
+        body,
+      });
     } catch (e) {
       addError('Could not send the request: ' + (e && e.message ? e.message : e)
              + ' — this failed in the browser before reaching the server.');
@@ -489,8 +500,9 @@ if (is_dir('/var/log/varaverk')) {
         addAnswer(j);
         history.push({ role: 'assistant', content: j.answer });
         if (history.length > MAXTURN * 2) history = history.slice(-MAXTURN * 2);
-        const fd = new FormData(); fd.append('action','clear'); fd.append('token',token);
-        fetch(API, { method:'POST', body: fd }).catch(() => {});
+        fetch(API, { method: 'POST',
+          headers: { 'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8' },
+          body: new URLSearchParams({ action: 'clear', token }) }).catch(() => {});
         finish(); loadBanner(); return;
       }
       if (j.status === 'error') { addError(j.error || 'Unknown error'); finish(); return; }