style: unify identifier naming per updated conventions

Automated with clang-tidy readability-identifier-naming (config added to
.clang-tidy) plus scripted passes, per the updated rules now documented
in CONTRIBUTING.md:

- types (class/struct/enum/alias/template params): PascalCase
- functions, variables, members: snake_case (incl. rational -> Rational)
- private/protected members: trailing underscore; static member
  variables likewise (instance_, available_themes_)
- constants and enum values: snake_case (kLinear -> k_linear,
  F32P -> f32p); ALL_CAPS reserved for macros
- macros: OAK_ prefix (OLIVE_ADD_TEST/OLIVE_ASSERT/OLIVE_CONFIG ->
  OAK_ADD_TEST/OAK_ASSERT/OAK_CONFIG, GL_PREAMBLE -> OAK_GL_PREAMBLE,
  include guards -> OAK_*)
- file names: all lowercase (Current/Plugin/OliveHost/OliveClip/
  OlivePluginInstance -> current/plugin/olivehost/oliveclip/
  oliveplugininstance)
- getters share the member name sans underscore, setters set_foo()
- Qt and third-party (OpenFX) virtual overrides and framework callbacks
  keep their original names (exempt in .clang-tidy)

Manual follow-ups required where automation could not reach:
- string-based QMetaObject/SIGNAL/SLOT references updated to renamed
  methods (AddTask, CreatedFile, DeleteSpecificFile, moveSelectionUp, ...)
- macro bodies referencing renamed methods (OLIVE_CONFIG,
  NODE_DEFAULT_DESTRUCTOR, MANAGEDDISPLAYWIDGET_*)
- self-shadowing locals renamed where signals/methods became same-named
  (size_changed, worker_count, selected_items, import param, filters)
- third_party OFX member/namespace usages restored (OFX::Host::*,
  _created, _clipPrefsDirty, createInstance, clearPersistentMessage)
- STL protocol aliases restored (const_iterator) with .clang-tidy
  ignore rules; qHash overloads restored

Full build and test suite pass: ctest 4/4, ~1960 gtest cases green.

app/codec/proxymanager.h

@@ -16,8 +16,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef PROXYMANAGER_H
-#define PROXYMANAGER_H
+#ifndef OAK_PROXYMANAGER_H
+#define OAK_PROXYMANAGER_H
 
 #include <QMutex>
 #include <QObject>
@@ -34,14 +34,14 @@ class ProxyTask;
 class ProxyManager : public QObject {
 	Q_OBJECT
 public:
-	static void CreateInstance()
+	static void create_instance()
 	{
 		if (!instance_) {
 			instance_ = new ProxyManager();
 		}
 	}
 
-	static void DestroyInstance()
+	static void destroy_instance()
 	{
 		delete instance_;
 		instance_ = nullptr;
@@ -53,10 +53,10 @@ public:
 	}
 
 	enum ProxyState {
-		kProxyMissing,
-		kProxyGenerating,
-		kProxyReady,
-		kProxyFailed
+		k_proxy_missing,
+		k_proxy_generating,
+		k_proxy_ready,
+		k_proxy_failed
 	};
 
 	struct ProxyParams {
@@ -70,36 +70,36 @@ public:
 	};
 
 	struct Proxy {
-		ProxyState state = kProxyMissing;
+		ProxyState state = k_proxy_missing;
 		QString filename;
 		ProxyTask *task = nullptr;
 	};
 
-	static QString GetProxyDirectory(const QString &cache_path);
+	static QString get_proxy_directory(const QString &cache_path);
 
-	static QString GetProxyFilename(const QString &cache_path,
+	static QString get_proxy_filename(const QString &cache_path,
 									const QString &source_filename,
 									int stream_index,
 									const ProxyParams &params);
 
-	static QString GetWorkingProxyFilename(const QString &proxy_filename);
+	static QString get_working_proxy_filename(const QString &proxy_filename);
 
-	static ProxyState GetProxyState(const QString &proxy_filename);
+	static ProxyState get_proxy_state(const QString &proxy_filename);
 
-	static QString ProxyStateToString(ProxyState state);
+	static QString proxy_state_to_string(ProxyState state);
 
-	static ProxyState ProxyStateFromString(const QString &state);
+	static ProxyState proxy_state_from_string(const QString &state);
 
 	/**
 	 * @brief Returns true if a proxy filename generated by GetProxyFilename()
 	 * indicates the proxy contains audio streams
 	 */
-	static bool ProxyFilenameHasAudio(const QString &proxy_filename);
+	static bool proxy_filename_has_audio(const QString &proxy_filename);
 
 	/**
 	 * @brief Builds proxy parameters from the global application config
 	 */
-	static ProxyParams ProxyParamsFromConfig();
+	static ProxyParams proxy_params_from_config();
 
 	/**
 	 * @brief Locates an ffmpeg executable for proxy generation
@@ -109,16 +109,16 @@ public:
 	 * platform-specific install locations. Returns an empty string if no
 	 * executable could be found.
 	 */
-	static QString FindFFmpegExecutable(const QString &configured_path);
+	static QString find_f_fmpeg_executable(const QString &configured_path);
 
-	Proxy GetOrStartProxy(const QString &cache_path,
+	Proxy get_or_start_proxy(const QString &cache_path,
 						  const QString &source_filename, int stream_index,
 						  const ProxyParams &params);
 
 signals:
-	void ProxyReady(const QString &source_filename, int stream_index,
+	void proxy_ready(const QString &source_filename, int stream_index,
 					const QString &proxy_filename);
-	void ProxyFinished(const QString &source_filename, int stream_index,
+	void proxy_finished(const QString &source_filename, int stream_index,
 					   const QString &proxy_filename, ProxyState state);
 
 private:
@@ -139,9 +139,9 @@ private:
 	QVector<ProxyData> proxying_;
 
 private slots:
-	void ProxyTaskFinished(Task *task, bool succeeded);
+	void proxy_task_finished(Task *task, bool succeeded);
 };
 
 }
 
-#endif // PROXYMANAGER_H
+#endif // OAK_PROXYMANAGER_H