feat(docs): enhance README and backend documentation for new user onboarding and backend conventions

- Added a "Start Here" section in both English and Chinese README files to guide new users on running the project locally and exploring its features.
- Introduced backend conventions for date and serialization handling, clarifying the use of Pydantic v2 and PostgreSQL.
- Updated the "Quick Start" section with detailed steps for first-time local setup, including environment requirements and backend setup instructions.
- Improved overall structure and clarity of documentation to facilitate better understanding for developers and contributors.

backend/app/plugin/module_task/cronjob/node/model.py

@@ -0,0 +1,28 @@
+from sqlalchemy import Boolean, Integer, String, Text
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.base_model import ModelMixin, UserMixin
+
+
+class NodeModel(ModelMixin, UserMixin):
+    """
+    节点类型模型 - 动态定义节点类型
+    """
+
+    __tablename__: str = "task_node"
+    __table_args__: dict[str, str] = {"comment": "节点类型表"}
+    __loader_options__: list[str] = ["created_by", "updated_by"]
+
+    name: Mapped[str] = mapped_column(String(64), nullable=False, comment="节点名称")
+    code: Mapped[str] = mapped_column(String(32), nullable=False, unique=True, comment="节点编码")
+    jobstore: Mapped[str | None] = mapped_column(String(64), nullable=True, default="default", comment="存储器")
+    executor: Mapped[str | None] = mapped_column(String(64), nullable=True, default="default", comment="执行器")
+    trigger: Mapped[str | None] = mapped_column(String(64), nullable=True, comment="触发器")
+    trigger_args: Mapped[str | None] = mapped_column(Text, nullable=True, comment="触发器参数")
+    func: Mapped[str | None] = mapped_column(Text, nullable=True, comment="代码块")
+    args: Mapped[str | None] = mapped_column(Text, nullable=True, comment="位置参数")
+    kwargs: Mapped[str | None] = mapped_column(Text, nullable=True, comment="关键字参数")
+    coalesce: Mapped[bool] = mapped_column(Boolean, nullable=True, default=False, comment="是否合并运行")
+    max_instances: Mapped[int] = mapped_column(Integer, nullable=True, default=1, comment="最大实例数")
+    start_date: Mapped[str | None] = mapped_column(String(64), nullable=True, comment="开始时间")
+    end_date: Mapped[str | None] = mapped_column(String(64), nullable=True, comment="结束时间")