fix: 修复文档多处不准确 + inference scheduler 越界 bug + SchedulerCallback 回调阶段修正

文档 (6 个文件):
- design.md: 15+ 处修正 — persistent_key_values→paged_cache,
  MLA 字段重写, Server/ParallelSetup 不存在类移除,
  关系箭头方向修复, SchedulerCallback 阶段修正等
- dataflow.md: 重写数据流图和描述, 修复训练回调顺序、
  数据键名、MLA 归属、MetricTracker 等错误
- introduction.md: 层数 32→24, MLP 图双 Linear 修正,
  默认值/响应字段/health 端点修复
- params.md: 补充 grpo 及 4 个 GRPO 参数
- README.md / README-zh-CN.md: generate.py 补全必需参数,
  删除重复注释, HuggingFace 声明修正

代码 (2 个文件):
- scheduler.py: n_pages 池加 page_size 余量防止越界;
  decode 前预分配页
- train_callback.py: SchedulerCallback 从 on_step_end 改
  回 on_batch_end (按 batch 步进学习率)

README.md

@@ -46,7 +46,7 @@
 - 💡 **Easy to Use**: Simple API with comprehensive examples and demos.
 - 📦 **Lightweight**: Minimal dependencies, easy to deploy.
 - 🔬 **Research‑Friendly**: Modular design, easy to experiment with new ideas.
-- 🤗 **HuggingFace Integration**: Compatible with HuggingFace models and datasets.
+- 🤗 **HuggingFace-Style API**: AutoModel/AutoTokenizer APIs inspired by HuggingFace for easy model and tokenizer loading.
 - 🔌 **Dual API Compatibility**: Supports both OpenAI and Anthropic chat completion APIs out of the box.
 
 ### Quick Start
@@ -84,7 +84,10 @@ Full reference at [Parameter Guide](assets/docs/params.md).
 #### Generate Text
 
 ```bash
-python scripts/tools/generate.py --param_path=/path/to/param_path
+python scripts/tools/generate.py \
+    --param_path /path/to/model \
+    --input_json_file /path/to/input.json \
+    --output_json_file /path/to/output.json
 ```
 
 #### Docker
@@ -117,8 +120,6 @@ docker compose --profile cpu up -d
 
 > **Note**: `--gpus all` is required for CUDA support. Without it, `torch.cuda.is_available()` will return `False`.
 
-> **Note**: `--gpus all` is required for CUDA support. Without it, `torch.cuda.is_available()` will return `False`.
-
 #### Start HTTP Server
 
 Start the inference server with OpenAI and Anthropic-compatible HTTP API: