Remove outdated references to 'DatabaseMigrator' (#1101)

## PR Type
- [ ] Feature
- [ ] Hotfix
- [ ] Release
- [x] Documentation

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## Checklist
- [x] Code builds locally
- [x] Tests added or updated
- [x] CI is green
- [ ] Peer review completed

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### UAT
- [ ] Required → completed
- [x] Not required (explain below)
Change to documentation

Author: carlsixsmith-moj

.github/copilot-instructions.md

@@ -42,7 +42,7 @@ The solution follows **Clean Architecture** with four main layers:
 
 Supporting projects:
 - `src/Aspire/Cats.AppHost` — Aspire orchestration host for local dev and Kubernetes publishing.
-- `src/DatabaseMigrator` — standalone migrator used during deployment.
+- `src/DatabaseSeeding` — standalone seeder used during deployment.
 
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README.md

@@ -54,7 +54,7 @@ The recommended way to run and debug these apps is using .NET Aspire.
 - **Using Visual Studio Code**: open the project and press `F5`, selecting the *Default Configuration*.
 - **Using Visual Studio or other IDEs**: From the debug configuration dropdown, select `Cats.AppHost` and start the application.
 
-On startup, Aspire automatically applies the SQL Project schema to the local SQL Server container before starting the application. The `DatabaseMigrator` project then runs to seed any required reference data. No manual migration steps are needed for local development.
+On startup, Aspire automatically applies the SQL Project schema to the local SQL Server container before starting the application. The `DatabaseSeeding` project then runs to seed any required reference data. No manual migration steps are needed for local development.
 
 ## Database schema
 
@@ -100,7 +100,7 @@ Available targets:
 The `Publish` target writes output to:
 
 - `artifacts/Server.UI`
-- `artifacts/DatabaseMigrator`
+- `artifacts/DatabaseSeeding`
 
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