refactor(cava): fix thread-safety, resource leaks, and style violations

Comprehensive refactor of the cava module backend and frontends.

Style & naming
- Rename Cava -> CavaRaw; snake_case methods -> lowerCamelCase
- Replace NULL with nullptr; replace C-style casts with static_cast
- Add explicit standard-library includes (<memory>, <string>, <chrono>)
- Fix missing trailing underscores on member variables

Architecture
- Remove Gtk::GLArea multiple inheritance in CavaGLSL (composition)
- Return std::unique_ptr from factory; add doAction() to GLSL variant
- Encapsulate thread timing arithmetic in AdaptiveDelay struct

Thread safety & correctness
- Replace raw sigc::signal with SafeSignal for cross-thread marshalling
- Fix data race between loadConfig() and out_thread_ (recursive_mutex)
- Fix audio_raw shallow-copy use-after-free via deep-copy AudioRaw payload
- Make loadConfig() exception-safe with CavaConfigGuard RAII
- Fix blocking read_thread_ race on shutdown (condition_variable + timeout join)
- Fix isSilent() data race (acquire pthread mutex)
- Eliminate doUpdate() recursion (iteration instead)
- Guard audio_raw_clean() against uninitialized state
- Fix format-icons underflow and cava_config buffer overflow
- Store config by value to prevent dangling references on reload
- Cache frontend config and refresh on runtime changes
- Fix signed-char icon lookup bug on x86
- Prevent Json::Value mutation bloat via const-ref lookups
- Broaden exception catches in worker threads (std::exception)

Resource management & GL robustness
- Fix OpenGL resource leaks (persist VBO/IBO/VAO; explicit destructor cleanup)
- Fix shader error handling crashes (valid infoLog allocation)
- Cache uniform locations instead of querying per frame
- Fix gradient color uninitialized stack memory (zero-init + clamped count)
- Fix shader time uniform integer division bug (float arithmetic)
- Add explicit VAO bind in onRender()
- Handle runtime surface config changes independently of shader changes
- Clamp negative gradient_count before GL upload

Follow-up
- Singleton API split (inst() + configure()) intentionally deferred to a
  dedicated PR because it changes the public constructor contract.

include/modules/cava/cavaRaw.hpp

@@ -1,30 +1,38 @@
 #pragma once
 
+#include <map>
+#include <string>
+
+#include <sigc++/connection.h>
+
 #include "ALabel.hpp"
 #include "cava_backend.hpp"
 
 namespace waybar::modules::cava {
 
-class Cava final : public ALabel, public sigc::trackable {
+class CavaRaw final : public ALabel {
  public:
-  Cava(const std::string&, const Json::Value&);
-  ~Cava() = default;
+  CavaRaw(const std::string&, const Json::Value&);
+  ~CavaRaw();
   auto doAction(const std::string& name) -> void override;
 
  private:
+  using Action = void (CavaRaw::*)();
+
   std::shared_ptr<CavaBackend> backend_;
   // Text to display
-  Glib::ustring label_text_{""};
+  Glib::ustring label_text_;
   bool silence_{false};
   bool hide_on_silence_{false};
-  std::string format_silent_{""};
-  int ascii_range_{0};
+  std::string format_silent_;
   // Cava method
-  void pause_resume();
+  void pauseResume();
   auto onUpdate(const std::string& input) -> void;
   auto onSilence() -> void;
   // ModuleActionMap
-  static inline std::map<const std::string, void (waybar::modules::cava::Cava::* const)()>
-      actionMap_{{"mode", &waybar::modules::cava::Cava::pause_resume}};
+  static const std::map<std::string, Action> actionMap_;
+
+  sigc::connection update_conn_;
+  sigc::connection silence_conn_;
 };
 }  // namespace waybar::modules::cava