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/EmailTemplateService.cs

@@ -0,0 +1,95 @@
+using System.Collections.Concurrent;
+using EmailApi.Data.Repositories.Contracts;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+
+namespace EmailApi.Data.Services;
+
+public sealed class EmailTemplateService : IEmailTemplateService
+{
+    private readonly IServiceScopeFactory _scopeFactory;
+    private readonly ILogger<EmailTemplateService> _logger;
+    private ConcurrentDictionary<string, string> _valueCache = new(StringComparer.OrdinalIgnoreCase);
+    private ConcurrentDictionary<string, string> _operatorCache = new(StringComparer.OrdinalIgnoreCase);
+    private DateTime _loadedAt = DateTime.MinValue;
+    private static readonly TimeSpan CacheTtl = TimeSpan.FromMinutes(10);
+
+    public EmailTemplateService(IServiceScopeFactory scopeFactory, ILogger<EmailTemplateService> logger)
+    {
+        _scopeFactory = scopeFactory;
+        _logger = logger;
+    }
+
+    public string Get(string key, string language = "en")
+    {
+        EnsureCacheLoaded();
+
+        if (_valueCache.TryGetValue(CacheKey(key, language), out var value))
+            return value;
+
+        if (!string.Equals(language, "en", StringComparison.OrdinalIgnoreCase)
+            && _valueCache.TryGetValue(CacheKey(key, "en"), out var fallback))
+            return fallback;
+
+        _logger.LogWarning("Email template not found: key={Key}, language={Language}", key, language);
+        return key;
+    }
+
+    public string Render(string key, string language, params (string Key, string Value)[] placeholders)
+    {
+        var template = Get(key, language);
+        foreach (var (k, v) in placeholders)
+            template = template.Replace($"{{{{{k}}}}}", v, StringComparison.OrdinalIgnoreCase);
+        return template;
+    }
+
+    public string? GetOperatorCopy(string key, string language)
+    {
+        EnsureCacheLoaded();
+
+        if (_operatorCache.TryGetValue(CacheKey(key, language), out var specific)
+            && !string.IsNullOrWhiteSpace(specific))
+            return specific;
+
+        // Fall back to first non-empty OperatorCopy in the cache
+        foreach (var val in _operatorCache.Values)
+        {
+            if (!string.IsNullOrWhiteSpace(val))
+                return val;
+        }
+
+        return null;
+    }
+
+    private void EnsureCacheLoaded()
+    {
+        if (DateTime.UtcNow - _loadedAt < CacheTtl) return;
+
+        try
+        {
+            using var scope = _scopeFactory.CreateScope();
+            var repo = scope.ServiceProvider.GetRequiredService<IEmailTemplateRepository>();
+            var rows = repo.GetAllAsync(CancellationToken.None).GetAwaiter().GetResult();
+
+            var freshValues = new ConcurrentDictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            var freshOperator = new ConcurrentDictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+
+            foreach (var row in rows)
+            {
+                freshValues[CacheKey(row.Key, row.Language)] = row.Value;
+                freshOperator[CacheKey(row.Key, row.Language)] = row.OperatorCopy;
+            }
+
+            _valueCache = freshValues;
+            _operatorCache = freshOperator;
+            _loadedAt = DateTime.UtcNow;
+            _logger.LogDebug("Email template cache refreshed. {Count} templates loaded.", rows.Count);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to refresh email template cache. Serving stale cache.");
+        }
+    }
+
+    private static string CacheKey(string key, string language) => $"{key}::{language}";
+}