Move RAG repository from rag-api to rag-data — consolidate data layer ownership

- Move IRagRepository, EfRagRepository, and VectorSerializer from rag-api/Data to rag-data/Repositories
- Add rag-api-models ProjectReference to rag-data.csproj for model type availability
- Delete rag-api/Data folder (no longer needed; all data access is now in rag-data)
- This aligns RAG with email-api and other services: all data code in the data project

Pattern: rag-api (API logic) → rag-data (repository, EF entities, migrations)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Apis/cv-matcher-data/CvMatcherDbContext.cs

@@ -5,8 +5,8 @@ namespace CvMatcher.Data;
 
 public sealed class CvMatcherDbContext : DbContext
 {
-    public const string SchemaName = "cvMatcher";
-    public const string MigrationTableName = "_Migrations";
+    public const string SchemaName = MigrationConstants.SchemaName;
+    public const string MigrationTableName = MigrationConstants.MigrationTableName;
 
     public CvMatcherDbContext(DbContextOptions<CvMatcherDbContext> options) : base(options)
     {