fix: bug-fix sweep across node, audio, render, plugin subsystems

Node core:
- MathNode/TrigonometryNode combo strings realigned with Operation enums
- mathbase scalar/vector operand pick no longer uses bitwise type checks
- NodeSetPositionAndDependenciesRecursively moves dependencies again
- RemoveAllKeyframes undo actually restores keyframes
- NodeGroup GetInputName null-deref guard, passthrough ids use input id
- NodeValueTable::Has is an exact type match; tag fallback only for
  empty tags; kStrCombo/kPushButton get data type names
- delete_all_keyframes no longer loops forever on unparented keyframes;
  keyframe-load failures propagate; rational interpolation falls back to
  double; OpacityEffect no longer leaks its internal MathNode

Audio/footage:
- AudioVisualWaveform: GetSummaryFromTime underflow OOB read, TrimIn
  prepend length bookkeeping, OverwriteSums source channel indexing
- PanNode inserts the pan value into the sample job (keyframed pan
  works); OutputParamsChanged is emitted on device change; PortAudio
  device indices are validated before Pa_GetDeviceInfo
- Footage: AdjustTimeByLoopMode no longer hangs/UBs on degenerate
  lengths, GetStreamIndex bounds-checked, CheckFootage clears stale
  state on missing files, failed probes are not cached,
  FootageDescription::Load requires its own root element

Render/track:
- ViewerOutput pushes the tagged samples value; TrackList disconnects
  the track-height lambda; GetTrackFromReference validity check
- RenderManager dummy backend: null-initialized threads, guarded
  decoder-cache/timer paths; Renderer::Destroy releases color cache
  shaders/textures; unknown dynamic backends no longer alias to oakgl
- SharedMemoryRegion POSIX attach validates segment size; ReadMessage
  skips blank lines instead of failing; GC counter clamped;
  IsRenderingCustomRange implemented; TimeOffsetNode gets a true
  inverse OutputTimeAdjustment; zero-speed clips return the held frame

Plugin/nodes:
- OliveClip: stored default region of definition is honored, on-demand
  images are cached; OliveHost sets host identity properties and logs
  instead of showing modal dialogs offscreen; Plugin.h dead decls gone
- DespillNode guards graph-less use with Rec.709 fallback; description
  typos fixed (despill, swirl); mosaic applies when only one axis
  matches; Windows-only Project filename separator test fixed

tests/gtest/render_workerpool_ipc_test.cpp

@@ -646,16 +646,12 @@ TEST(IpcMessage, ReadMessageSkipsBlankLines)
 	const QByteArray line =
 		QJsonDocument(cancel.ToJson()).toJson(QJsonDocument::Compact);
 
-	// A reader loop sees: blank line, whitespace-only line, then a real message.
+	// A reader loop sees: blank line, whitespace-only line, then a real
+	// message. Blank lines are skipped silently.
 	QByteArray reader = QByteArray("\n   \n") + line + '\n';
 
 	QJsonObject obj;
 	bool ok = true;
-	EXPECT_FALSE(olive::ipc::ReadMessage(&reader, &obj, &ok)); // blank
-	EXPECT_FALSE(ok);
-	EXPECT_FALSE(olive::ipc::ReadMessage(&reader, &obj, &ok)); // whitespace
-	EXPECT_FALSE(ok);
-
 	ASSERT_TRUE(olive::ipc::ReadMessage(&reader, &obj, &ok));
 	EXPECT_TRUE(ok);
 	olive::ipc::CancelMsg back;