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/20260524145351_AddTemplates.cs

@@ -1,5 +1,6 @@
 using System;
 using Microsoft.EntityFrameworkCore.Migrations;
+using MyAi.Data;
 
 #nullable disable
 
@@ -12,11 +13,11 @@ namespace MyAi.Data.Migrations
         protected override void Up(MigrationBuilder migrationBuilder)
         {
             migrationBuilder.EnsureSchema(
-                name: "myAi");
+                name: MigrationConstants.SchemaName);
 
             migrationBuilder.CreateTable(
                 name: "Templates",
-                schema: "myAi",
+                schema: MigrationConstants.SchemaName,
                 columns: table => new
                 {
                     Key = table.Column<string>(type: "nvarchar(128)", maxLength: 128, nullable: false),
@@ -36,7 +37,7 @@ namespace MyAi.Data.Migrations
         private static void Seed(MigrationBuilder m)
         {
             void Row(string key, string lang, string value, string description = "")
-                => m.InsertData("Templates", ["Key", "Language", "Value", "Description"], [key, lang, value, description], "myAi");
+                => m.InsertData("Templates", ["Key", "Language", "Value", "Description"], [key, lang, value, description], MigrationConstants.SchemaName);
 
             // Match result email — subject
             Row("email.match.subject", "en", "MyAi.ro CV Match: {{score}}% - {{jobLabel}}", "Subject for the CV match result email");
@@ -107,7 +108,7 @@ namespace MyAi.Data.Migrations
         {
             migrationBuilder.DropTable(
                 name: "Templates",
-                schema: "myAi");
+                schema: MigrationConstants.SchemaName);
         }
     }
 }