feat(theming): integrate NvChad chadrc rewrite into Apply

internal/theming/theming.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"github.com/MDietermann/ArduinoArchSetup/internal/config"
+	"github.com/MDietermann/ArduinoArchSetup/internal/modules/neovim"
 	"github.com/MDietermann/ArduinoArchSetup/internal/platform"
 	"gopkg.in/yaml.v3"
 )
@@ -144,6 +145,15 @@ func Apply(cfg config.Config, themeID string) error {
 	if err := updateOverlayActive(th.ID); err != nil {
 		return fmt.Errorf("update overlay: %w", err)
 	}
+
+	if err := neovim.WriteChadrc(th.NvChadTheme); err != nil {
+		return fmt.Errorf("update chadrc: %w", err)
+	}
+
+	// Clear NvChad's base46 theme cache so the new theme activates on next
+	// nvim launch. Errors ignored — the cache may not exist.
+	_ = os.RemoveAll(filepath.Join(home, ".cache", "nvim", "base46"))
+	_ = os.RemoveAll(filepath.Join(home, ".local", "share", "nvim", "lazy", "base46", "lua", "base46", "themes"))
 	return nil
 }