Initial commit: PESCO NCR system

Complete Non-Conformance Report system replacing the PowerApps/SharePoint
prototype: FastAPI + SQLAlchemy 2 (async) + Alembic + MySQL 8 backend,
React 18 + Vite + TypeScript + MUI frontend, Entra ID auth (MSAL / JWKS,
group-gated), Microsoft Graph delegated Mail.Send notifications (OBO),
six-stage workflow state machine with server-side enforcement, atomic
NCR-YYYY-NNNN numbering, attachments with camera capture, immutable
field-level audit trail, admin reopen, reports + CSV export, WeasyPrint
PDF traveler, Power BI reporting views + read-only DB user, documented
VISUAL ERP job-lookup stub, pytest suite (26 tests), docker-compose
deployment.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/app/models/app_setting.py

@@ -0,0 +1,14 @@
+from sqlalchemy import String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.models.base import Base
+
+
+class AppSetting(Base):
+    __tablename__ = "app_settings"
+
+    key: Mapped[str] = mapped_column(String(100), primary_key=True)
+    value: Mapped[str] = mapped_column(String(500))
+
+
+NOTIFICATIONS_ENABLED_KEY = "notifications_enabled"