fix(chat): replay tool_calls in history so tool context survives follow-ups

The history builder was silently dropping tool_calls from prior turns,
causing the LLM to lose article/search context on every follow-up.
Now reconstructs the assistant tool_call dict + per-call tool result
entries. Messages without tool_calls are unaffected.

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

src/fabledassistant/routes/chat.py

@@ -162,8 +162,19 @@ async def send_message_route(conv_id: int):
     # Build history from existing messages (excluding system and the placeholder)
     history = []
     for msg in conv.messages:
-        if msg.role != "system":
-            history.append({"role": msg.role, "content": msg.content})
+        if msg.role == "system":
+            continue
+        msg_dict = {"role": msg.role, "content": msg.content or ""}
+        if msg.tool_calls:
+            msg_dict["tool_calls"] = [
+                {"function": {"name": tc["function"], "arguments": tc["arguments"]}}
+                for tc in msg.tool_calls
+            ]
+            history.append(msg_dict)
+            for tc in msg.tool_calls:
+                history.append({"role": "tool", "content": json.dumps(tc.get("result", {}))})
+        else:
+            history.append(msg_dict)
 
     model = await get_setting(uid, "default_model", Config.OLLAMA_MODEL) or Config.OLLAMA_MODEL