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/widget/viewer/viewersizer.h

@@ -19,8 +19,8 @@
 
 ***/
 
-#ifndef VIEWERSIZER_H
-#define VIEWERSIZER_H
+#ifndef OAK_VIEWERSIZER_H
+#define OAK_VIEWERSIZER_H
 
 #include <olive/core/core.h>
 #include <QScrollBar>
@@ -50,12 +50,12 @@ public:
    *
    * ViewerSizer takes ownership of this widget. If a widget was previously set, it is destroyed.
    */
-	void SetWidget(QWidget *widget);
+	void set_widget(QWidget *widget);
 
-	QSize GetContainerSize() const;
+	QSize get_container_size() const;
 
-	static constexpr int kZoomLevelCount = 10;
-	static constexpr double kZoomLevels[kZoomLevelCount] = {
+	static constexpr int k_zoom_level_count = 10;
+	static constexpr double k_zoom_levels[k_zoom_level_count] = {
 		0.05, 0.1, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 4.0, 8.0
 	};
 
@@ -65,29 +65,29 @@ public slots:
    *
    * This is not the actual resolution of the viewer, it's used to calculate the aspect ratio
    */
-	void SetChildSize(int width, int height);
+	void set_child_size(int width, int height);
 
 	/**
    * @brief Set pixel aspect ratio
    */
-	void SetPixelAspectRatio(const rational &pixel_aspect);
+	void set_pixel_aspect_ratio(const Rational &pixel_aspect);
 
 	/**
    * @brief Set the zoom value of the child widget
    *
    * The number is an integer percentage (100 = 100%). Set to 0 to auto-fit.
    */
-	void SetZoom(double percent);
-	void SetZoomAnchored(double percent, double cursor_x, double cursor_y);
+	void set_zoom(double percent);
+	void set_zoom_anchored(double percent, double cursor_x, double cursor_y);
 
-	void HandDragMove(int x, int y);
+	void hand_drag_move(int x, int y);
 
 	virtual bool eventFilter(QObject *watched, QEvent *event) override;
 
 signals:
-	void RequestScale(const QMatrix4x4 &matrix);
+	void request_scale(const QMatrix4x4 &matrix);
 
-	void RequestTranslate(const QMatrix4x4 &matrix);
+	void request_translate(const QMatrix4x4 &matrix);
 
 protected:
 	/**
@@ -99,11 +99,11 @@ private:
 	/**
    * @brief Main sizing function, resizes widget_ to fit aspect_ratio_ (or hides if aspect ratio is 0)
    */
-	void UpdateSize();
+	void update_size();
 
-	int GetZoomedValue(int value);
+	int get_zoomed_value(int value);
 
-	double GetRealCurrentZoom() const;
+	double get_real_current_zoom() const;
 
 	/**
    * @brief Reference to widget
@@ -118,7 +118,7 @@ private:
 	int width_;
 	int height_;
 
-	rational pixel_aspect_;
+	Rational pixel_aspect_;
 
 	/**
    * @brief Internal zoom value
@@ -130,9 +130,9 @@ private:
 	QScrollBar *vert_scrollbar_;
 
 private slots:
-	void ScrollBarMoved();
+	void scroll_bar_moved();
 };
 
 }
 
-#endif // VIEWERSIZER_H
+#endif // OAK_VIEWERSIZER_H