Unzip budget-app v7 into repo root

budget-app/backend/app/audit.py

@@ -0,0 +1,25 @@
+from decimal import Decimal
+
+from sqlalchemy.orm import Session
+
+from .models import AuditEntry, User
+
+
+def _plain(value):
+    if isinstance(value, Decimal):
+        return str(value.normalize()) if value == value.to_integral() else str(value)
+    return value
+
+
+def snapshot(obj, fields: list[str]) -> dict:
+    return {f: _plain(getattr(obj, f)) for f in fields}
+
+
+def diff(before: dict, after: dict) -> dict:
+    return {k: [before.get(k), after.get(k)] for k in after if before.get(k) != after.get(k)}
+
+
+def record(db: Session, user: User | None, entity: str, entity_id: int | None, action: str,
+           summary: str = "", changes: dict | None = None, year_id: int | None = None) -> None:
+    db.add(AuditEntry(user_id=user.id if user else None, entity=entity, entity_id=entity_id,
+                      action=action, summary=summary[:500], changes=changes, year_id=year_id))