feat: add email-api-data project with EmailTemplates repository and service

New data project owning the emailApi schema:
- EmailTemplateEntity with Key, Language, Value, Description, UpdatedAt, OperatorCopy
- EmailApiDbContext (schema: emailApi, custom migration table _EmailApiMigrations)
- IEmailTemplateRepository / EfEmailTemplateRepository (scoped)
- IEmailTemplateService / EmailTemplateService (singleton, 10-min cache)
  - GetOperatorCopy falls back to first non-empty OperatorCopy across all rows
- Initial migration CreateEmailTemplates: creates table + seeds all email.*
  templates (match + search-results in en/ro) and html-shell fragments
  with OperatorCopy = "contact@myai.ro" for addressable rows

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Apis/email-api-data/Services/IEmailTemplateService.cs

@@ -0,0 +1,8 @@
+namespace EmailApi.Data.Services;
+
+public interface IEmailTemplateService
+{
+    string Get(string key, string language = "en");
+    string Render(string key, string language, params (string Key, string Value)[] placeholders);
+    string? GetOperatorCopy(string key, string language);
+}