fix: use relative API URLs so fetch works under blueprint prefix

app/tools/ai_debate_arena/templates/ai_debate_arena/index.html

@@ -264,7 +264,7 @@
     btnPdf.classList.add('hidden');
 
     try {
-      const res = await fetch('/api/debate', {
+      const res = await fetch('api/debate', {
         method: 'POST',
         headers: { 'Content-Type': 'application/json', 'X-CSRFToken': CSRF },
         body: JSON.stringify({ proposition, language: langSelect.value })

app/tools/content_repurposer/templates/content_repurposer/index.html

@@ -271,7 +271,7 @@ function updateCharCount() {
     fd.append('file', file);
 
     try {
-      const res  = await fetch('/api/upload', {
+      const res  = await fetch('api/upload', {
         method: 'POST',
         headers: { 'X-CSRFToken': _csrf },
         body: fd,
@@ -316,7 +316,7 @@ async function repurpose() {
   }, 1400);
 
   try {
-    const res  = await fetch('/api/repurpose', {
+    const res  = await fetch('api/repurpose', {
       method:  'POST',
       headers: {'Content-Type': 'application/json', 'X-CSRFToken': _csrf},
       body:    JSON.stringify({
@@ -424,7 +424,7 @@ function renderResults(results) {
 }
 
 async function downloadResult(fmt, text) {
-  const res = await fetch('/api/download', {
+  const res = await fetch('api/download', {
     method: 'POST',
     headers: {'Content-Type': 'application/json', 'X-CSRFToken': _csrf},
     body: JSON.stringify({format: fmt, text})