fix(cava): default data_format to ascii for correct bar scaling

data_format was changed from always "ascii" to user-configurable,
but without a default. This caused cava to use "binary", calculating
height as 65535 instead of ascii_range, making bars always peak.

Author: xav-ie

src/modules/cava/cava_backend.cpp

@@ -186,6 +186,10 @@ void waybar::modules::cava::CavaBackend::loadConfig() {
   if (config_["data_format"].isString()) {
     if (prm_.data_format) free(prm_.data_format);
     prm_.data_format = strdup(config_["data_format"].asString().c_str());
+  } else {
+    // Default to ascii for format-icons output
+    if (prm_.data_format) free(prm_.data_format);
+    prm_.data_format = strdup("ascii");
   }
   if (config_["raw_target"].isString()) {
     if (prm_.raw_target) free(prm_.raw_target);