feat: 实现成长路径功能

- 新增数据库表: growth_path_nodes, user_growth_path_progress, user_node_completions
- 新增 Model: GrowthPathNode, UserGrowthPathProgress, UserNodeCompletion
- 新增 Service: GrowthPathService（管理端CRUD、学员端进度追踪）
- 新增 API: 学员端获取成长路径、管理端CRUD
- 前端学员端从API动态加载成长路径数据
- 更新管理端API接口定义

backend/app/models/growth_path.py

@@ -0,0 +1,206 @@
+"""
+成长路径相关数据库模型
+"""
+from enum import Enum
+from typing import List, Optional
+from datetime import datetime
+from decimal import Decimal
+
+from sqlalchemy import (
+    String,
+    Text,
+    Integer,
+    Boolean,
+    ForeignKey,
+    Enum as SQLEnum,
+    JSON,
+    DateTime,
+    DECIMAL,
+)
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.models.base import BaseModel, SoftDeleteMixin
+
+
+class GrowthPathStatus(str, Enum):
+    """成长路径学习状态"""
+    NOT_STARTED = "not_started"  # 未开始
+    IN_PROGRESS = "in_progress"  # 进行中
+    COMPLETED = "completed"      # 已完成
+
+
+class NodeStatus(str, Enum):
+    """节点状态"""
+    LOCKED = "locked"          # 锁定（前置未完成）
+    UNLOCKED = "unlocked"      # 已解锁（可以开始）
+    IN_PROGRESS = "in_progress"  # 学习中
+    COMPLETED = "completed"    # 已完成
+
+
+class GrowthPathNode(BaseModel, SoftDeleteMixin):
+    """
+    成长路径节点表
+    每个节点对应一门课程
+    """
+    __tablename__ = "growth_path_nodes"
+
+    # 关联
+    growth_path_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("growth_paths.id", ondelete="CASCADE"),
+        nullable=False,
+        comment="成长路径ID"
+    )
+    course_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("courses.id", ondelete="CASCADE"),
+        nullable=False,
+        comment="课程ID"
+    )
+
+    # 节点信息
+    stage_name: Mapped[Optional[str]] = mapped_column(
+        String(100), nullable=True, comment="所属阶段名称"
+    )
+    title: Mapped[str] = mapped_column(
+        String(200), nullable=False, comment="节点标题"
+    )
+    description: Mapped[Optional[str]] = mapped_column(
+        Text, nullable=True, comment="节点描述"
+    )
+
+    # 配置
+    order_num: Mapped[int] = mapped_column(
+        Integer, default=0, nullable=False, comment="排序顺序"
+    )
+    is_required: Mapped[bool] = mapped_column(
+        Boolean, default=True, nullable=False, comment="是否必修"
+    )
+    prerequisites: Mapped[Optional[List[int]]] = mapped_column(
+        JSON, nullable=True, comment="前置节点IDs"
+    )
+    estimated_days: Mapped[int] = mapped_column(
+        Integer, default=7, nullable=False, comment="预计学习天数"
+    )
+
+    # 关联关系
+    growth_path: Mapped["GrowthPath"] = relationship(
+        "GrowthPath", back_populates="nodes"
+    )
+    course: Mapped["Course"] = relationship("Course")
+    user_completions: Mapped[List["UserNodeCompletion"]] = relationship(
+        "UserNodeCompletion", back_populates="node"
+    )
+
+
+class UserGrowthPathProgress(BaseModel):
+    """
+    用户成长路径进度表
+    记录用户在某条成长路径上的整体进度
+    """
+    __tablename__ = "user_growth_path_progress"
+
+    # 关联
+    user_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        comment="用户ID"
+    )
+    growth_path_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("growth_paths.id", ondelete="CASCADE"),
+        nullable=False,
+        comment="成长路径ID"
+    )
+
+    # 进度信息
+    current_node_id: Mapped[Optional[int]] = mapped_column(
+        Integer, nullable=True, comment="当前学习节点ID"
+    )
+    completed_node_ids: Mapped[Optional[List[int]]] = mapped_column(
+        JSON, nullable=True, comment="已完成节点IDs"
+    )
+    total_progress: Mapped[Decimal] = mapped_column(
+        DECIMAL(5, 2), default=0.00, nullable=False, comment="总进度百分比"
+    )
+
+    # 状态
+    status: Mapped[str] = mapped_column(
+        String(20),
+        default=GrowthPathStatus.NOT_STARTED.value,
+        nullable=False,
+        comment="状态"
+    )
+
+    # 时间记录
+    started_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True, comment="开始时间"
+    )
+    completed_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True, comment="完成时间"
+    )
+    last_activity_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True, comment="最后活动时间"
+    )
+
+    # 关联关系
+    user: Mapped["User"] = relationship("User")
+    growth_path: Mapped["GrowthPath"] = relationship("GrowthPath")
+
+
+class UserNodeCompletion(BaseModel):
+    """
+    用户节点完成记录表
+    详细记录用户在每个节点上的学习状态
+    """
+    __tablename__ = "user_node_completions"
+
+    # 关联
+    user_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        comment="用户ID"
+    )
+    growth_path_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("growth_paths.id", ondelete="CASCADE"),
+        nullable=False,
+        comment="成长路径ID"
+    )
+    node_id: Mapped[int] = mapped_column(
+        Integer,
+        ForeignKey("growth_path_nodes.id", ondelete="CASCADE"),
+        nullable=False,
+        comment="节点ID"
+    )
+
+    # 进度信息
+    course_progress: Mapped[Decimal] = mapped_column(
+        DECIMAL(5, 2), default=0.00, nullable=False, comment="课程学习进度"
+    )
+    status: Mapped[str] = mapped_column(
+        String(20),
+        default=NodeStatus.LOCKED.value,
+        nullable=False,
+        comment="状态"
+    )
+
+    # 时间记录
+    unlocked_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True, comment="解锁时间"
+    )
+    started_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True, comment="开始学习时间"
+    )
+    completed_at: Mapped[Optional[datetime]] = mapped_column(
+        DateTime(timezone=True), nullable=True, comment="完成时间"
+    )
+
+    # 关联关系
+    user: Mapped["User"] = relationship("User")
+    node: Mapped["GrowthPathNode"] = relationship(
+        "GrowthPathNode", back_populates="user_completions"
+    )
+    growth_path: Mapped["GrowthPath"] = relationship("GrowthPath")