refactor: upgrade to Go 1.26 and modernize code idioms

- Replace `interface{}` with `any` type alias across all packages
- Use built-in `min()`/`max()` for parameter clamping
- Use `slices.SortFunc`, `slices.Min`, `slices.Max` for cleaner code
- Use `strings.Cut()` for simpler string parsing in auth middleware
- Use `errors.Is()` for proper error comparison in handlers
- Update dependencies: golang.org/x/image 0.37.0 -> 0.38.0
- Add Wire code generation guidelines to ARCHITECTURE.md
- Disable Go cache in CI build workflow

internal/dto/notification_converter.go

@@ -54,7 +54,7 @@ func SystemMessageToResponse(msg *model.Message) *SystemMessageResponse {
 		CreatedAt:  msg.CreatedAt,
 	}
 	if msg.ExtraData != nil {
-		resp.ExtraData = map[string]interface{}{
+		resp.ExtraData = map[string]any{
 			"actor_id":    msg.ExtraData.ActorID,
 			"actor_name":  msg.ExtraData.ActorName,
 			"avatar_url":  msg.ExtraData.AvatarURL,
@@ -92,7 +92,7 @@ func SystemNotificationToResponse(n *model.SystemNotification) *SystemMessageRes
 		CreatedAt:  n.CreatedAt,
 	}
 	if n.ExtraData != nil {
-		resp.ExtraData = map[string]interface{}{
+		resp.ExtraData = map[string]any{
 			"actor_id":           n.ExtraData.ActorID,
 			"actor_id_str":       n.ExtraData.ActorIDStr,
 			"actor_name":         n.ExtraData.ActorName,