feat: add employee management, backend health check, and UI improvements

server/src/app/models/organization.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+import uuid
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, String, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.db.base_class import Base
+
+
+class OrganizationUnit(Base):
+    __tablename__ = "organization_units"
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=lambda: str(uuid.uuid4()))
+    unit_code: Mapped[str] = mapped_column(String(50), unique=True, index=True)
+    name: Mapped[str] = mapped_column(String(100), index=True)
+    unit_type: Mapped[str] = mapped_column(String(30), default="department", index=True)
+    parent_id: Mapped[str | None] = mapped_column(
+        ForeignKey("organization_units.id"), nullable=True, index=True
+    )
+    cost_center: Mapped[str | None] = mapped_column(String(50), nullable=True)
+    location: Mapped[str | None] = mapped_column(String(100), nullable=True)
+    manager_name: Mapped[str | None] = mapped_column(String(100), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now()
+    )
+
+    parent = relationship("OrganizationUnit", remote_side=[id], back_populates="children")
+    children = relationship("OrganizationUnit", back_populates="parent")
+    employees = relationship("Employee", back_populates="organization_unit")