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/node/input/time/timeinput.cpp

@@ -30,7 +30,7 @@ TimeInput::TimeInput()
 {
 }
 
-QString TimeInput::Name() const
+QString TimeInput::name() const
 {
 	return tr("Time");
 }
@@ -40,20 +40,20 @@ QString TimeInput::id() const
 	return QStringLiteral("org.olivevideoeditor.Olive.time");
 }
 
-QVector<Node::CategoryID> TimeInput::Category() const
+QVector<Node::CategoryID> TimeInput::category() const
 {
-	return { kCategoryTime };
+	return { k_category_time };
 }
 
-QString TimeInput::Description() const
+QString TimeInput::description() const
 {
 	return tr("Generates the time (in seconds) at this frame.");
 }
 
-void TimeInput::Value(const NodeValueRow &value, const NodeGlobals &globals,
+void TimeInput::value(const NodeValueRow &value, const NodeGlobals &globals,
 					  NodeValueTable *table) const
 {
-	table->Push(NodeValue::kFloat, globals.time().in().toDouble(), this, false,
+	table->push(NodeValue::k_float, globals.time().in().to_double(), this, false,
 				QStringLiteral("time"));
 }