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/cavaGLSL.hpp

@@ -1,36 +1,64 @@
 #pragma once
 
 #include <epoxy/gl.h>
+#include <gtkmm/glarea.h>
+#include <map>
+#include <string>
+#include <array>
+
+#include <sigc++/connection.h>
 
 #include "AModule.hpp"
 #include "cava_backend.hpp"
 
 namespace waybar::modules::cava {
 
-class CavaGLSL final : public AModule, public Gtk::GLArea {
+class CavaGLSL final : public AModule {
  public:
   CavaGLSL(const std::string&, const Json::Value&);
-  ~CavaGLSL() = default;
+  ~CavaGLSL();
+  auto doAction(const std::string& name) -> void override;
 
  private:
+  using Action = void (CavaGLSL::*)();
+
+  Gtk::GLArea gl_area_;
   std::shared_ptr<CavaBackend> backend_;
-  struct ::cava::config_params prm_;
-  int frame_counter{0};
+  // Cached config params (deep-copied strings to avoid dangling char* on backend reload)
+  int sdl_width_{0};
+  int sdl_height_{0};
+  int bar_width_{0};
+  int bar_spacing_{0};
+  int gradient_count_{0};
+  std::string vertex_shader_;
+  std::string fragment_shader_;
+  std::string bcolor_;
+  std::string color_;
+  std::array<std::string, 8> gradient_colors_;
+  int frame_counter_{0};
   bool silence_{false};
   bool hide_on_silence_{false};
+  bool mapped_{false};
   // Cava method
-  auto onUpdate(const ::cava::audio_raw& input) -> void;
+  void pauseResume();
+  auto onUpdate(const CavaBackend::AudioRaw& input) -> void;
   auto onSilence() -> void;
-  // Member variable to store the shared pointer
-  std::shared_ptr<::cava::audio_raw> m_data_;
-  GLuint shaderProgram_;
+  auto onBackendConfigChanged() -> void;
+  void cacheConfigParams(const ::cava::config_params& src);
+  // Member variable to store audio data
+  CavaBackend::AudioRaw m_data_;
+  GLuint shaderProgram_{0};
   // OpenGL variables
-  GLuint fbo_;
-  GLuint texture_;
+  GLuint fbo_{0};
+  GLuint texture_{0};
+  GLuint vbo_{0};
+  GLuint ibo_{0};
+  GLuint vao_{0};
   GLint uniform_bars_;
   GLint uniform_previous_bars_;
   GLint uniform_bars_count_;
   GLint uniform_time_;
+  GLint uniform_input_texture_;
   // Methods
   void onRealize();
   bool onRender(const Glib::RefPtr<Gdk::GLContext>& context);
@@ -39,5 +67,13 @@ class CavaGLSL final : public AModule, public Gtk::GLArea {
   void initSurface();
   void initGLSL();
   GLuint loadShader(const std::string& fileName, GLenum type);
+  void cleanupGL();
+
+  // ModuleActionMap
+  static const std::map<std::string, Action> actionMap_;
+
+  sigc::connection audio_raw_update_conn_;
+  sigc::connection silence_conn_;
+  sigc::connection config_changed_conn_;
 };
 }  // namespace waybar::modules::cava