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/myai-data/Migrations/20260527120000_UpdateEmailTemplatesToHtml.cs

@@ -1,4 +1,5 @@
 using Microsoft.EntityFrameworkCore.Migrations;
+using MyAi.Data;
 
 #nullable disable
 
@@ -12,7 +13,7 @@ namespace MyAi.Data.Migrations
         {
             void Update(string key, string lang, string value)
                 => migrationBuilder.UpdateData("Templates", ["Key", "Language"], [key, lang],
-                    ["Value"], [value], "myAi");
+                    ["Value"], [value], MigrationConstants.SchemaName);
 
             // email.match.body — en
             Update("email.match.body", "en",
@@ -120,7 +121,7 @@ namespace MyAi.Data.Migrations
         {
             void Update(string key, string lang, string value)
                 => migrationBuilder.UpdateData("Templates", ["Key", "Language"], [key, lang],
-                    ["Value"], [value], "myAi");
+                    ["Value"], [value], MigrationConstants.SchemaName);
 
             Update("email.match.body", "en",
                 "CV Matcher result\n\nCV Document ID: {{cvDocumentId}}\nJob: {{jobLabel}}\nJob URL: {{jobUrl}}\nScore: {{score}}%\n\nSummary:\n{{summary}}\n\nStrengths:\n{{strengths}}\n\nGaps:\n{{gaps}}\n\nRecommendations:\n{{recommendations}}");