init: EasyScreen 电子菜单系统

- server: FastAPI 后端（多屏管理、素材上传、节目编排、客户端注册/配置/心跳/崩溃上报、管理台托管）
- android: Java 客户端（minSdk 23，全屏图片/视频轮播、远程配置、开机自启、崩溃上报）
- web: React + Vite + antd 管理台（屏幕/素材/节目管理）
- 屏幕设备 ID 关联机制、gunicorn 生产部署脚本

server/app/models.py

@@ -0,0 +1,98 @@
+"""数据模型：屏幕设备、素材、节目、节目项、屏幕绑定。"""
+from datetime import datetime
+
+from sqlalchemy import (
+    Boolean,
+    DateTime,
+    ForeignKey,
+    Integer,
+    String,
+    Text,
+    UniqueConstraint,
+)
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from .database import Base
+
+
+class Screen(Base):
+    """显示屏设备。device_id 由客户端首次启动时生成并注册。"""
+
+    __tablename__ = "screens"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    name: Mapped[str] = mapped_column(String(100), default="未命名屏幕")
+    device_id: Mapped[str] = mapped_column(String(64), unique=True, index=True)
+    location: Mapped[str] = mapped_column(String(200), default="")
+    status: Mapped[str] = mapped_column(String(20), default="offline")  # online/offline
+    last_seen: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.now)
+
+    bindings: Mapped[list["ScreenBinding"]] = relationship(
+        back_populates="screen", cascade="all, delete-orphan"
+    )
+
+
+class Asset(Base):
+    """媒体素材：图片或视频。url 为相对于 /media 的路径。"""
+
+    __tablename__ = "assets"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    name: Mapped[str] = mapped_column(String(200))
+    type: Mapped[str] = mapped_column(String(20))  # image / video
+    url: Mapped[str] = mapped_column(String(500))
+    size: Mapped[int] = mapped_column(Integer, default=0)
+    duration: Mapped[int] = mapped_column(Integer, default=0)  # 图片默认展示秒数；视频为0表示按视频时长
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.now)
+
+    items: Mapped[list["PlaylistItem"]] = relationship(back_populates="asset")
+
+
+class Playlist(Base):
+    """节目：一组素材的轮播清单。"""
+
+    __tablename__ = "playlists"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    name: Mapped[str] = mapped_column(String(100))
+    description: Mapped[str] = mapped_column(Text, default="")
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.now)
+
+    items: Mapped[list["PlaylistItem"]] = relationship(
+        back_populates="playlist", cascade="all, delete-orphan", order_by="PlaylistItem.sort_order"
+    )
+    bindings: Mapped[list["ScreenBinding"]] = relationship(
+        back_populates="playlist", cascade="all, delete-orphan"
+    )
+
+
+class PlaylistItem(Base):
+    """节目项：素材 + 排序 + 可选展示时长覆盖。"""
+
+    __tablename__ = "playlist_items"
+    __table_args__ = (UniqueConstraint("playlist_id", "sort_order", name="uq_playlist_sort"),)
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    playlist_id: Mapped[int] = mapped_column(ForeignKey("playlists.id", ondelete="CASCADE"), index=True)
+    asset_id: Mapped[int] = mapped_column(ForeignKey("assets.id", ondelete="CASCADE"), index=True)
+    sort_order: Mapped[int] = mapped_column(Integer, default=0)
+    duration: Mapped[int | None] = mapped_column(Integer, nullable=True)  # 覆盖素材默认时长(秒)
+
+    playlist: Mapped[Playlist] = relationship(back_populates="items")
+    asset: Mapped[Asset] = relationship(back_populates="items")
+
+
+class ScreenBinding(Base):
+    """屏幕与节目的绑定。一个屏幕同时只有一个 active=True 的绑定。"""
+
+    __tablename__ = "screen_bindings"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    screen_id: Mapped[int] = mapped_column(ForeignKey("screens.id", ondelete="CASCADE"), index=True)
+    playlist_id: Mapped[int] = mapped_column(ForeignKey("playlists.id", ondelete="CASCADE"), index=True)
+    active: Mapped[bool] = mapped_column(Boolean, default=True)
+    updated_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.now, onupdate=datetime.now)
+
+    screen: Mapped[Screen] = relationship(back_populates="bindings")
+    playlist: Mapped[Playlist] = relationship(back_populates="bindings")