Initial commit: Backend API Phase 1a complete

- FastAPI backend with JWT auth
- PostgreSQL database schema
- Trees and Sessions CRUD APIs
- Export functionality (Markdown, Text, HTML)
- Docker setup for local development
- Alembic migrations

backend/app/schemas/tree.py

@@ -0,0 +1,52 @@
+from datetime import datetime
+from typing import Optional, Any
+from uuid import UUID
+from pydantic import BaseModel, Field
+
+
+class TreeBase(BaseModel):
+    name: str = Field(..., min_length=1, max_length=255)
+    description: Optional[str] = None
+    category: Optional[str] = Field(None, max_length=100)
+
+
+class TreeCreate(TreeBase):
+    tree_structure: dict[str, Any] = Field(..., description="The decision tree structure in JSON format")
+
+
+class TreeUpdate(BaseModel):
+    name: Optional[str] = Field(None, min_length=1, max_length=255)
+    description: Optional[str] = None
+    category: Optional[str] = Field(None, max_length=100)
+    tree_structure: Optional[dict[str, Any]] = None
+    is_active: Optional[bool] = None
+
+
+class TreeResponse(TreeBase):
+    id: UUID
+    tree_structure: dict[str, Any]
+    author_id: Optional[UUID] = None
+    team_id: Optional[UUID] = None
+    is_active: bool
+    version: int
+    created_at: datetime
+    updated_at: datetime
+    usage_count: int
+
+    class Config:
+        from_attributes = True
+
+
+class TreeListResponse(BaseModel):
+    id: UUID
+    name: str
+    description: Optional[str] = None
+    category: Optional[str] = None
+    is_active: bool
+    version: int
+    usage_count: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True