Initial commit: audio2text 双语字幕生成服务

- 音频/视频转双语(英/中)SRT 字幕，Docker 容器化，CPU 开发/GPU 生产同一份代码
- faster-whisper ASR(词级时间戳) + 断句时间戳重算 + NLLB 翻译(模型不共驻)
- 分片上传(断点续传) + SQLite 持久化 + 主页/历史/日志页面
- 历史页文件名搜索；缓存定时清理(默认保留7天，可配置)
- 双 Dockerfile(cpu/gpu) + setup/start/stop 脚本

app/models/upload_session.py

@@ -0,0 +1,49 @@
+"""分片上传会话 ORM：支撑断点续传。对齐 server 的 UploadSession 形态（SQLite 版）。"""
+
+from __future__ import annotations
+
+import json
+from datetime import datetime, timezone
+from typing import Any
+
+from sqlalchemy import DateTime, ForeignKey, Integer, String, Text, TypeDecorator
+from sqlalchemy.orm import Mapped, mapped_column
+
+from ..database import Base
+
+
+def _now() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+class _IntList(TypeDecorator):
+    """把 list[int] 存成 JSON 字符串。SQLite 没有 ARRAY 类型。"""
+
+    impl = Text
+    cache_ok = True
+
+    def process_bind_param(self, value: Any, dialect) -> str | None:
+        return json.dumps(value) if value is not None else None
+
+    def process_result_value(self, value: Any, dialect) -> list[int]:
+        return json.loads(value) if value else []
+
+
+class UploadSession(Base):
+    __tablename__ = "upload_session"
+
+    upload_id: Mapped[str] = mapped_column(String(64), primary_key=True)
+    filename: Mapped[str] = mapped_column(String(512), nullable=False)
+    size_bytes: Mapped[int] = mapped_column(Integer, nullable=False)
+    chunk_size: Mapped[int] = mapped_column(Integer, nullable=False)
+    total_chunks: Mapped[int] = mapped_column(Integer, nullable=False)
+    uploaded_chunks: Mapped[list[int]] = mapped_column(_IntList, default=list)
+    # pending → completed（complete 成功）| abandoned（reaper 清理）
+    status: Mapped[str] = mapped_column(String(32), nullable=False, default="pending")
+    # 拼接完成后的视频相对 upload_dir 路径
+    final_path: Mapped[str | None] = mapped_column(String(1024), nullable=True)
+    # complete 后关联的 Task.id（直接引用，避免反向查找 source_path）
+    task_id: Mapped[int | None] = mapped_column(ForeignKey("task.id"), nullable=True)
+
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=_now)
+    updated_at: Mapped[datetime] = mapped_column(DateTime, default=_now, onupdate=_now)