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.

ffmpeg_bridge/src/sws.cpp

@@ -30,8 +30,8 @@ FBScaler *fb_scaler_create(int src_width, int src_height, int src_format,
 						   int flags)
 {
 	SwsContext *ctx = sws_getContext(
-		src_width, src_height, fb::PixFmtToAV(src_format),
-		dst_width, dst_height, fb::PixFmtToAV(dst_format), flags,
+		src_width, src_height, fb::pix_fmt_to_av(src_format),
+		dst_width, dst_height, fb::pix_fmt_to_av(dst_format), flags,
 		nullptr, nullptr, nullptr);
 	if (!ctx) {
 		return nullptr;
@@ -58,7 +58,7 @@ int fb_scaler_set_colorspace(FBScaler *scaler, int colorspace, int jpeg_range)
 	}
 
 	const int *coeffs = sws_getCoefficients(
-		fb::SwsColorspaceFromAVColorSpace(static_cast<AVColorSpace>(colorspace)));
+		fb::sws_colorspace_from_av_color_space(static_cast<AVColorSpace>(colorspace)));
 	return sws_setColorspaceDetails(scaler->ctx, coeffs, jpeg_range, coeffs,
 									jpeg_range, 0, 0x10000, 0x10000);
 }
@@ -85,7 +85,7 @@ int fb_scaler_scale_slices(FBScaler *scaler, const uint8_t *const *src_data,
 void fb_get_yuv_coefficients(int colorspace, double out[4])
 {
 	const int *coeffs = sws_getCoefficients(
-		fb::SwsColorspaceFromAVColorSpace(static_cast<AVColorSpace>(colorspace)));
+		fb::sws_colorspace_from_av_color_space(static_cast<AVColorSpace>(colorspace)));
 	// Matches the historical usage order: crv, cbu, cgu, cgv
 	out[0] = coeffs[0] / 65536.0; // crv
 	out[1] = coeffs[1] / 65536.0; // cbu