feat: 添加 context_rewrite 工具并清理工具限制器死配置

- 新增 context_rewrite 工具：允许 AI 在单轮内压缩工具调用上下文
- 清理 persona_query_max 和 task_query_max 死配置（commit 9be60ba 引入）
- 同步全栈：后端/前端/文档/测试 18 个文件
- 测试：70/70 通过

tests/test_core/test_packet.py

@@ -192,7 +192,7 @@ class TestBackendClientAPI:
         
         result = client.update_settings(
             api_config={"api_key": "new-key", "base_url": "https://api.deepseek.com", "model": "deepseek-chat"},
-            tool_limits={"persona_query_max": 2}
+            tool_limits={"persona_update_max": 2}
         )
         assert result.get("success") is True
         
@@ -282,8 +282,10 @@ class TestToolLimiter:
     def test_tool_limiter_init(self):
         from core.tool_limiter import ToolLimiter
         limiter = ToolLimiter()
-        assert limiter.counts.persona_query == 0
         assert limiter.counts.persona_update == 0
+        assert limiter.counts.task_update == 0
+        assert limiter.counts.memory_query == 0
+        assert limiter.counts.memory_update == 0
 
     def test_tool_limiter_classify(self):
         from core.tool_limiter import ToolLimiter