Feat: refine dataflow and initialize dataflow app (#9952)

### What problem does this PR solve?

Refine dataflow and initialize dataflow app.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

rag/flow/tokenizer/schema.py

@@ -0,0 +1,51 @@
+#
+#  Copyright 2025 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+from typing import Any, Literal
+
+from pydantic import BaseModel, ConfigDict, Field, model_validator
+
+
+class TokenizerFromUpstream(BaseModel):
+    created_time: float | None = Field(default=None, alias="_created_time")
+    elapsed_time: float | None = Field(default=None, alias="_elapsed_time")
+
+    name: str = ""
+    blob: bytes
+
+    output_format: Literal["json", "markdown", "text", "html"] | None = Field(default=None)
+
+    chunks: list[dict[str, Any]] | None = Field(default=None)
+
+    json_result: list[dict[str, Any]] | None = Field(default=None, alias="json")
+    markdown_result: str | None = Field(default=None, alias="markdown")
+    text_result: str | None = Field(default=None, alias="text")
+    html_result: str | None = Field(default=None, alias="html")
+
+    model_config = ConfigDict(populate_by_name=True, extra="forbid")
+
+    @model_validator(mode="after")
+    def _check_payloads(self) -> "TokenizerFromUpstream":
+        if self.chunks:
+            return self
+
+        if self.output_format in {"markdown", "text"}:
+            if self.output_format == "markdown" and not self.markdown_result:
+                raise ValueError("output_format=markdown requires a markdown payload (field: 'markdown' or 'markdown_result').")
+            if self.output_format == "text" and not self.text_result:
+                raise ValueError("output_format=text requires a text payload (field: 'text' or 'text_result').")
+        else:
+            if not self.json_result:
+                raise ValueError("When no chunks are provided and output_format is not markdown/text, a JSON list payload is required (field: 'json' or 'json_result').")
+        return self