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/dialog/sequence/sequencedialogpresettab.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef SEQUENCEDIALOGPRESETTAB_H
-#define SEQUENCEDIALOGPRESETTAB_H
+#ifndef OAK_SEQUENCEDIALOGPRESETTAB_H
+#define OAK_SEQUENCEDIALOGPRESETTAB_H
 
 #include <QLabel>
 #include <QTreeWidget>
@@ -39,33 +39,33 @@ public:
 	SequenceDialogPresetTab(QWidget *parent = nullptr);
 
 public slots:
-	void SaveParametersAsPreset(SequencePreset preset);
+	void save_parameters_as_preset(SequencePreset preset);
 
 signals:
-	void PresetChanged(const SequencePreset &preset);
+	void preset_changed(const SequencePreset &preset);
 
-	void PresetAccepted();
+	void preset_accepted();
 
 private:
-	QTreeWidgetItem *CreateFolder(const QString &name);
+	QTreeWidgetItem *create_folder(const QString &name);
 
-	QTreeWidgetItem *CreateHDPresetFolder(const QString &name, int width,
+	QTreeWidgetItem *create_hd_preset_folder(const QString &name, int width,
 										  int height, int divider);
 
-	QTreeWidgetItem *CreateSDPresetFolder(
-		const QString &name, int width, int height, const rational &frame_rate,
-		const rational &standard_par, const rational &wide_par, int divider);
+	QTreeWidgetItem *create_sd_preset_folder(
+		const QString &name, int width, int height, const Rational &frame_rate,
+		const Rational &standard_par, const Rational &wide_par, int divider);
 
-	QTreeWidgetItem *GetSelectedItem();
-	QTreeWidgetItem *GetSelectedCustomPreset();
+	QTreeWidgetItem *get_selected_item();
+	QTreeWidgetItem *get_selected_custom_preset();
 
-	void AddStandardItem(QTreeWidgetItem *folder, PresetPtr preset,
+	void add_standard_item(QTreeWidgetItem *folder, PresetPtr preset,
 						 const QString &description = QString());
 
-	void AddCustomItem(QTreeWidgetItem *folder, PresetPtr preset, int index,
+	void add_custom_item(QTreeWidgetItem *folder, PresetPtr preset, int index,
 					   const QString &description = QString());
 
-	void AddItemInternal(QTreeWidgetItem *folder, PresetPtr preset,
+	void add_item_internal(QTreeWidgetItem *folder, PresetPtr preset,
 						 bool is_custom, int index,
 						 const QString &description = QString());
 
@@ -76,16 +76,16 @@ private:
 	QVector<PresetPtr> default_preset_data_;
 
 private slots:
-	void SelectedItemChanged(QTreeWidgetItem *current,
+	void selected_item_changed(QTreeWidgetItem *current,
 							 QTreeWidgetItem *previous);
 
-	void ItemDoubleClicked(QTreeWidgetItem *item, int column);
+	void item_double_clicked(QTreeWidgetItem *item, int column);
 
-	void ShowContextMenu();
+	void show_context_menu();
 
-	void DeleteSelectedPreset();
+	void delete_selected_preset();
 };
 
 }
 
-#endif // SEQUENCEDIALOGPRESETTAB_H
+#endif // OAK_SEQUENCEDIALOGPRESETTAB_H