feat: add Buchhaltung module with fiscal years, budget accounts, transactions, and approval workflow

backend/src/app.ts

@@ -107,6 +107,7 @@ import buchungskategorieRoutes from './routes/buchungskategorie.routes';
 import checklistRoutes         from './routes/checklist.routes';
 import fahrzeugTypRoutes       from './routes/fahrzeugTyp.routes';
 import ausruestungTypRoutes    from './routes/ausruestungTyp.routes';
+import buchhaltungRoutes        from './routes/buchhaltung.routes';
 
 app.use('/api/auth',        authRoutes);
 app.use('/api/user',        userRoutes);
@@ -136,6 +137,7 @@ app.use('/api/buchungskategorien', buchungskategorieRoutes);
 app.use('/api/checklisten',       checklistRoutes);
 app.use('/api/fahrzeug-typen',    fahrzeugTypRoutes);
 app.use('/api/ausruestung-typen', ausruestungTypRoutes);
+app.use('/api/buchhaltung',      buchhaltungRoutes);
 
 // Static file serving for uploads (authenticated)
 const uploadsDir = process.env.NODE_ENV === 'production' ? '/app/uploads' : path.resolve(__dirname, '../../uploads');