fix(chat): complete streaming for reasoning, tools, and tool calls

- Forward reasoning_content and non-stream reasoning to on_token in
  OpenAI chat completions; Gemini thought parts to on_token.
- Stream bubble: always render session.tool panels; format tool_use_call
  payloads and title as call · tool_name.
- Emit tool_use_call via on_tool_ui before tool execution so WS shows
  invoke cards before tool_use_result.

Co-authored-by: Cursor <cursoragent@cursor.com>

platform/llm/transports/google_gemini_sse.py

@@ -224,6 +224,8 @@ class GoogleGeminiChatModel(ChatModel):
                                 txt = str(p.get("text") or "")
                                 if txt:
                                     thinking_parts.append(txt)
+                                    if on_token:
+                                        on_token(txt)
                                 sig = p.get("thoughtSignature")
                                 if isinstance(sig, str) and sig:
                                     thinking_signature = sig