Initial commit: Purrse personal finance app

Self-hosted, plugin-extensible personal finance manager built with
ASP.NET Core 9.0, Vue 3 + Vuetify 3, and PostgreSQL 17.

Backend (8 .NET projects):
- Core: 19 domain models, 6 enums, 14 DTOs, 12 service interfaces
- Data: EF Core DbContext, 16 entity configurations, category seeder
- API: 14 controllers, 15 services, JWT auth, SignalR, middleware
- Plugins: Abstractions + OFX/CSV/QIF file parsers
- Tests: 28 xUnit tests (fingerprinting, duplicate detection, parsers)

Frontend (Vue 3 + Vuetify 3 + TypeScript):
- 13 views, Pinia stores, Axios API services with JWT interceptors
- Dashboard, accounts, transactions, categories, imports, and more

Deployment:
- Docker Compose (PostgreSQL 17 + .NET API + nginx frontend)
- Auto-migration on startup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/Purrse.Core/Models/InvestmentHolding.cs

@@ -0,0 +1,14 @@
+namespace Purrse.Core.Models;
+
+public class InvestmentHolding
+{
+    public Guid Id { get; set; }
+    public Guid AccountId { get; set; }
+    public Guid SecurityId { get; set; }
+    public decimal Shares { get; set; }
+    public decimal CostBasis { get; set; }
+    public DateTime AsOfDate { get; set; }
+
+    public Account Account { get; set; } = null!;
+    public Security Security { get; set; } = null!;
+}