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

backend/app/db/base.py

@@ -1,5 +0,0 @@
-from sqlalchemy.orm import DeclarativeBase
-
-
-class Base(DeclarativeBase):
-    pass

backend/app/db/session.py

@@ -1,9 +1,16 @@
 from __future__ import annotations
 
-from sqlalchemy import create_engine
-from sqlalchemy.orm import sessionmaker
+from sqlmodel import Session, SQLModel, create_engine
 
 from app.core.config import settings
 
-engine = create_engine(settings.database_url, pool_pre_ping=True)
-SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+engine = create_engine(settings.database_url, echo=False)
+
+
+def init_db() -> None:
+    SQLModel.metadata.create_all(engine)
+
+
+def get_session():
+    with Session(engine) as session:
+        yield session