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/Entities/EmailTemplateEntity.cs

@@ -0,0 +1,12 @@
+namespace EmailApi.Data.Entities;
+
+// composite PK (Key + Language) — BaseEntity not applicable
+public sealed class EmailTemplateEntity
+{
+    public string Key { get; set; } = string.Empty;
+    public string Language { get; set; } = string.Empty;
+    public string Value { get; set; } = string.Empty;
+    public string Description { get; set; } = string.Empty;
+    public DateTime UpdatedAt { get; set; }
+    public string OperatorCopy { get; set; } = string.Empty;
+}