Fix category shadow foreign keys and .NET 10 Docker build context

ARCHITECTURE.md

@@ -1801,6 +1801,34 @@ var importer = new TransactionImporter(mockDb.Object, mockCardResolver.Object);
 
 ## Deployment
 
+### Docker image build (.NET 10)
+
+Run from the repository root (not `MoneyMap/`):
+
+```bash
+docker build -f MoneyMap/Dockerfile -t moneymap:local .
+```
+
+The Dockerfile uses the .NET 10 SDK and ASP.NET Core 10 runtime. The root
+context is required to copy `MoneyMap.sln` and the shared `MoneyMap.Core`
+project. The root `.dockerignore` excludes local build output, receipts,
+database files, and all `appsettings*.json`/credential files. Supply runtime
+configuration separately via environment variables (for example
+`ConnectionStrings__MoneyMapDb`, `OPENAI_API_KEY`) or a mounted
+configuration file; credentials are not baked into the image. Building does
+not start the application or apply migrations.
+
+### Category relationship mapping
+
+`Transaction.Category` and `CategoryMapping.Category` remain string category
+names. The corresponding collections on `Category` are `[NotMapped]` so EF
+cannot infer nonexistent `CategoryId` shadow foreign keys. The real
+`RecurringPlace.CategoryId` and parent/child category relationships remain
+mapped. This is a model correction only, with no database schema change or
+migration required. SQL Server model/query regression tests compile both
+receipt duplicate-check queries without connecting to a database.
+
+
 ### Database Migration
 ```bash
 # Create migration