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/render/ipc/sharedmemoryregion.h

@@ -18,8 +18,8 @@
 
 ***/
 
-#ifndef IPC_SHAREDMEMORYREGION_H
-#define IPC_SHAREDMEMORYREGION_H
+#ifndef OAK_IPC_SHAREDMEMORYREGION_H
+#define OAK_IPC_SHAREDMEMORYREGION_H
 
 #include <cstddef>
 #include <QString>
@@ -46,9 +46,9 @@ class SharedMemoryRegion {
 public:
 	enum Mode {
 		/// Create (and own) the segment. Fails if it already exists; unlinks on destruction.
-		kCreate,
+		k_create,
 		/// Attach to a segment created by the peer. Does not unlink on destruction.
-		kAttach
+		k_attach
 	};
 
 	SharedMemoryRegion();
@@ -63,14 +63,14 @@ public:
    * `key` is a short identifier (no leading slash needed; the platform prefix is added internally).
    * Returns true on success. On failure, error() carries a human-readable reason.
    */
-	bool Open(const QString &key, size_t size, Mode mode);
+	bool open(const QString &key, size_t size, Mode mode);
 
 	/**
    * @brief Unmap and (if owner) unlink the segment. Called automatically by the destructor.
    */
-	void Close();
+	void close();
 
-	bool IsValid() const
+	bool is_valid() const
 	{
 		return data_ != nullptr;
 	}
@@ -100,7 +100,7 @@ public:
    *
    * Centralized so the owner and the spawned worker agree on the same name.
    */
-	static QString MakeKey(qint64 owner_pid, int worker_index);
+	static QString make_key(qint64 owner_pid, int worker_index);
 
 private:
 	QString key_;
@@ -120,4 +120,4 @@ private:
 } // namespace ipc
 } // namespace olive
 
-#endif // IPC_SHAREDMEMORYREGION_H
+#endif // OAK_IPC_SHAREDMEMORYREGION_H