Stream AI responses (SSE) - text appears as it generates

- Backend streams tokens via Server-Sent Events
- Frontend reads stream with fetch + ReadableStream
- Edit mode: document updates live as tokens arrive
- Chat mode: response text appears progressively
- No more waiting for full generation to complete

frontend/src/App.vue

@@ -1014,21 +1014,45 @@ async function sendAiChat() {
 
   const action = aiChatMode.value === 'edit' ? 'edit' : 'chat'
   try {
-    const res = await api('/api/ai/chat', {
-      path: currentFile.value,
-      content: content.value,
-      message: msg,
-      mode: action,
+    const res = await fetch('/api/ai/chat', {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json', 'Authorization': 'Bearer ' + token.value },
+      body: JSON.stringify({ path: currentFile.value, content: content.value, message: msg, mode: action }),
     })
-    if (action === 'edit' && res.content) {
-      content.value = res.content
+
+    const reader = res.body.getReader()
+    const decoder = new TextDecoder()
+    let fullText = ''
+    let buffer = ''
+
+    while (true) {
+      const { done, value } = await reader.read()
+      if (done) break
+      buffer += decoder.decode(value, { stream: true })
+      const lines = buffer.split('\n')
+      buffer = lines.pop()
+      for (const line of lines) {
+        if (!line.startsWith('data: ')) continue
+        const data = line.slice(6)
+        if (data === '[DONE]') break
+        try {
+          const token_text = JSON.parse(data)
+          fullText += token_text
+          if (action === 'edit') {
+            content.value = fullText
+          } else {
+            aiChatResponse.value = fullText
+          }
+        } catch {}
+      }
+    }
+
+    if (action === 'edit') {
       isDirty.value = true
       aiChatResponse.value = 'Document updated.'
-    } else {
-      aiChatResponse.value = res.result || res.content || 'No response'
     }
   } catch (e) {
-    aiChatResponse.value = 'AI request failed. Check MH_AI_ENDPOINT.'
+    aiChatResponse.value = 'AI request failed.'
   }
   aiChatLoading.value = false
 }