feat(i18n): add LocaleStore folder discovery

src/ClaudeDo.Localization/LocaleStore.cs

@@ -0,0 +1,31 @@
+namespace ClaudeDo.Localization;
+
+public sealed class LocaleStore
+{
+    private readonly Dictionary<string, LocaleFile> _byCode;
+
+    private LocaleStore(Dictionary<string, LocaleFile> byCode) => _byCode = byCode;
+
+    public IReadOnlyList<LocaleFile> Available => _byCode.Values.ToList();
+
+    public bool TryGet(string code, out LocaleFile? file) => _byCode.TryGetValue(code, out file);
+
+    public static LocaleStore Load(string folder)
+    {
+        var byCode = new Dictionary<string, LocaleFile>(StringComparer.OrdinalIgnoreCase);
+        if (Directory.Exists(folder))
+        {
+            foreach (var path in Directory.EnumerateFiles(folder, "*.json"))
+            {
+                try
+                {
+                    var file = LocaleJson.Parse(File.ReadAllText(path));
+                    if (!string.IsNullOrWhiteSpace(file.Code))
+                        byCode[file.Code] = file;
+                }
+                catch { /* skip malformed locale files */ }
+            }
+        }
+        return new LocaleStore(byCode);
+    }
+}