Refactor backend to SQLModel; reset schema; add Company OS endpoints

backend/app/models/org.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from typing import Optional
+
+from sqlmodel import Field, SQLModel
+
+
+class Department(SQLModel, table=True):
+    __tablename__ = "departments"
+
+    id: int | None = Field(default=None, primary_key=True)
+    name: str = Field(index=True, unique=True)
+    head_employee_id: int | None = Field(default=None, foreign_key="employees.id")
+
+
+class Employee(SQLModel, table=True):
+    __tablename__ = "employees"
+
+    id: int | None = Field(default=None, primary_key=True)
+    name: str
+    employee_type: str  # human | agent
+
+    department_id: int | None = Field(default=None, foreign_key="departments.id")
+    manager_id: int | None = Field(default=None, foreign_key="employees.id")
+
+    title: str | None = None
+    status: str = Field(default="active")