Add is_default flag for system trees

- Add is_default column to trees table
- Default trees have no author and are visible to all users
- Only admins can create default trees
- Update seed script to mark seeded trees as default
- Update seed script to use CLI auth instead of creating seed user

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/api/endpoints/trees.py

@@ -120,13 +120,17 @@ async def create_tree(
     current_user: Annotated[User, Depends(require_engineer_or_admin)]
 ):
     """Create a new tree (engineers and admins only)."""
+    # Only admins can create default/system trees
+    is_default = tree_data.is_default and current_user.role == "admin"
+
     new_tree = Tree(
         name=tree_data.name,
         description=tree_data.description,
         category=tree_data.category,
         tree_structure=tree_data.tree_structure,
-        author_id=current_user.id,
-        team_id=current_user.team_id
+        author_id=None if is_default else current_user.id,  # Default trees have no author
+        team_id=None if is_default else current_user.team_id,
+        is_default=is_default
     )
     db.add(new_tree)
     await db.commit()

backend/app/models/tree.py

@@ -31,6 +31,7 @@ class Tree(Base):
         index=True
     )
     is_active: Mapped[bool] = mapped_column(Boolean, default=True)
+    is_default: Mapped[bool] = mapped_column(Boolean, default=False, index=True)
     version: Mapped[int] = mapped_column(Integer, default=1)
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True),

backend/app/schemas/tree.py

@@ -12,6 +12,7 @@ class TreeBase(BaseModel):
 
 class TreeCreate(TreeBase):
     tree_structure: dict[str, Any] = Field(..., description="The decision tree structure in JSON format")
+    is_default: bool = Field(False, description="Mark as a default/system tree (admin only)")
 
 
 class TreeUpdate(BaseModel):
@@ -28,6 +29,7 @@ class TreeResponse(TreeBase):
     author_id: Optional[UUID] = None
     team_id: Optional[UUID] = None
     is_active: bool
+    is_default: bool
     version: int
     created_at: datetime
     updated_at: datetime
@@ -43,6 +45,7 @@ class TreeListResponse(BaseModel):
     description: Optional[str] = None
     category: Optional[str] = None
     is_active: bool
+    is_default: bool
     version: int
     usage_count: int
     created_at: datetime