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/oiio/oiioencoder.cpp

@@ -31,21 +31,21 @@ OIIOEncoder::OIIOEncoder(const EncodingParams &params)
 {
 }
 
-bool OIIOEncoder::Open()
+bool OIIOEncoder::open()
 {
 	return true;
 }
 
-bool OIIOEncoder::WriteFrame(FramePtr frame, rational time)
+bool OIIOEncoder::write_frame(FramePtr frame, Rational time)
 {
-	std::string filename = GetFilenameForFrame(time).toStdString();
+	std::string filename = get_filename_for_frame(time).toStdString();
 
 	auto output = OIIO::ImageOutput::create(filename);
 	if (!output) {
 		return false;
 	}
 
-	OIIO::TypeDesc type = OIIOUtils::GetOIIOBaseTypeFromFormat(frame->format());
+	OIIO::TypeDesc type = OIIOUtils::get_oiio_base_type_from_format(frame->format());
 	OIIO::ImageSpec spec(frame->width(), frame->height(),
 						 frame->channel_count(), type);
 
@@ -65,18 +65,18 @@ bool OIIOEncoder::WriteFrame(FramePtr frame, rational time)
 	return true;
 }
 
-bool OIIOEncoder::WriteAudio(const SampleBuffer &audio)
+bool OIIOEncoder::write_audio(const SampleBuffer &audio)
 {
 	// Do nothing
 	return false;
 }
 
-bool OIIOEncoder::WriteSubtitle(const SubtitleBlock *sub_block)
+bool OIIOEncoder::write_subtitle(const SubtitleBlock *sub_block)
 {
 	return false;
 }
 
-void OIIOEncoder::Close()
+void OIIOEncoder::close()
 {
 	// Do nothing
 }