Stream model pull progress via SSE instead of fire-and-forget

Replace the asyncio.create_task() fire-and-forget pattern for model
downloads with SSE streaming that relays Ollama's pull progress in
real time. The frontend now shows live download percentage instead of
a static "Pulling..." label with blind polling.

- routes/chat.py: SSE streaming endpoint with 1800s timeout
- stores/settings.ts: pullModel uses apiStreamPost with onProgress callback
- SettingsView.vue: live "Downloading 42%" display, removed polling/setTimeout
- summary.md: updated to reflect SSE streaming for model pulls

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/fabledassistant/routes/chat.py

@@ -15,7 +15,7 @@ from fabledassistant.services.chat import (
     summarize_conversation_as_note,
     update_conversation_title,
 )
-from fabledassistant.services.llm import build_context, ensure_model, stream_chat
+from fabledassistant.services.llm import build_context, stream_chat
 from fabledassistant.services.settings import get_setting
 
 logger = logging.getLogger(__name__)
@@ -201,15 +201,40 @@ async def list_models_route():
 
 @chat_bp.route("/models/pull", methods=["POST"])
 async def pull_model_route():
-    """Pull a model from Ollama. Runs in the background."""
+    """Pull a model from Ollama, streaming progress via SSE."""
     data = await request.get_json()
     model_name = data.get("model", "").strip()
     if not model_name:
         return jsonify({"error": "model is required"}), 400
 
-    import asyncio
-    asyncio.create_task(ensure_model(model_name))
-    return jsonify({"status": "pulling", "model": model_name}), 202
+    async def generate():
+        try:
+            async with httpx.AsyncClient(timeout=1800.0) as client:
+                async with client.stream(
+                    "POST",
+                    f"{Config.OLLAMA_URL}/api/pull",
+                    json={"name": model_name},
+                ) as resp:
+                    resp.raise_for_status()
+                    async for line in resp.aiter_lines():
+                        if not line.strip():
+                            continue
+                        progress = json.loads(line)
+                        event_data = json.dumps(progress)
+                        yield f"data: {event_data}\n\n"
+            yield f"data: {json.dumps({'status': 'success'})}\n\n"
+        except Exception as e:
+            logger.exception("Error pulling model %s", model_name)
+            yield f"data: {json.dumps({'error': str(e)})}\n\n"
+
+    return Response(
+        generate(),
+        content_type="text/event-stream",
+        headers={
+            "Cache-Control": "no-cache",
+            "X-Accel-Buffering": "no",
+        },
+    )
 
 
 @chat_bp.route("/models/delete", methods=["POST"])