feat(i18n): initialize Localizer at app startup from config/OS culture

src/ClaudeDo.App/Program.cs

@@ -1,8 +1,10 @@
 using Avalonia;
 using ClaudeDo.Data;
 using ClaudeDo.Data.Git;
+using ClaudeDo.Localization;
 using ClaudeDo.Releases;
 using ClaudeDo.Ui;
+using ClaudeDo.Ui.Localization;
 using ClaudeDo.Ui.Services;
 using ClaudeDo.Ui.Services.Interfaces;
 using ClaudeDo.Ui.ViewModels;
@@ -12,6 +14,9 @@ using ClaudeDo.Ui.ViewModels.Modals.Settings;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using System;
+using System.Globalization;
+using System.IO;
+using System.Linq;
 using System.Net.Http;
 using System.Reflection;
 using System.Runtime.InteropServices;
@@ -71,6 +76,17 @@ sealed class Program
 
         // Infrastructure
         sc.AddSingleton(settings);
+        var localesDir = Path.Combine(AppContext.BaseDirectory, "locales");
+        var localeStore = LocaleStore.Load(localesDir);
+        var initialLang = !string.IsNullOrWhiteSpace(settings.Language)
+            ? settings.Language
+            : CultureResolver.Resolve(
+                CultureInfo.CurrentUICulture.Name,
+                localeStore.Available.Select(l => l.Code).ToArray(),
+                fallback: "en");
+        var localizer = new Localizer(localeStore, initialLang);
+        TrExtension.Localizer = localizer;
+        sc.AddSingleton<ILocalizer>(localizer);
         sc.AddDbContextFactory<ClaudeDoDbContext>(opt =>
             opt.UseSqlite($"Data Source={dbPath}"));
         sc.AddScoped<ClaudeDoDbContext>(sp =>