fix : 修复 created 时间戳、bin 多 shard 覆盖与文档遗漏

- openai.py/anthropic.py: created 从 0 改为 int(time.time())
- openai.py: ChatCompletionRequest 不支持参数非默认值时 warning
- pipeline.py: bin 多 shard 使用子目录避免静默覆盖
- storage.py: MmapStore/detect_format 支持多 shard 聚合加载
- architecture.md: mermaid 类图新增 Pipeline 类
- preprocessing.md: 新增多 shard 输出布局与 Python API 示例
- protocol.py: docstring "6 methods" 改为 "5 methods"

assets/docs/architecture.md

@@ -363,6 +363,16 @@ classDiagram
         class TextMaskBuilder {
             +build(item, config, tokenizer) Optional[dict]
         }
+
+        class Pipeline {
+            +PipelineConfig config
+            +List[str] paths
+            +str output_dir
+            +str tokenizer_path
+            +BaseMaskBuilder mask_builder
+            +transform(item) Optional[dict]
+            +run()
+        }
     }
 
     namespace tokenize {
@@ -1092,6 +1102,8 @@ classDiagram
     KvcacheView o-- Storage
     SamplingPipeline o-- BaseSamplingStrategy
     BaseDataset o-- Store
+    Pipeline o-- PipelineConfig
+    Pipeline o-- BaseMaskBuilder
 
     %% --- Dependency (uses temporarily) ---
     TrainConfig ..> BaseStrategy : selects