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

backend/app/schemas/work.py

@@ -0,0 +1,27 @@
+from __future__ import annotations
+
+from sqlmodel import SQLModel
+
+
+class TaskCreate(SQLModel):
+    project_id: int
+    title: str
+    description: str | None = None
+    status: str = "backlog"
+    assignee_employee_id: int | None = None
+    reviewer_employee_id: int | None = None
+    created_by_employee_id: int | None = None
+
+
+class TaskUpdate(SQLModel):
+    title: str | None = None
+    description: str | None = None
+    status: str | None = None
+    assignee_employee_id: int | None = None
+    reviewer_employee_id: int | None = None
+
+
+class TaskCommentCreate(SQLModel):
+    task_id: int
+    author_employee_id: int | None = None
+    body: str