build/ci: green builds and tests on all three platforms

Compiler hygiene (all platforms):
- Silence warnings across the tree: missing override, -Wreorder ctor
  init, -Wshadow, -Wsign-compare, missing switch cases, unused
  functions/captures, Qt 6.11 deprecations (QMouseEvent/QDropEvent
  accessors, qAsConst, Q_FOREACH over non-shared containers,
  AA_UseHighDpiPixmaps) and the .bak/ backup tree removal.
- Fix regressions from the cleanup: missing clip decls in
  capi/timeline.cpp, plugin.cpp rename fallout, panel setFocus
  ambiguity, QGraphicsItem::pos vs event->position(), duplicate
  k_push_button case, boolean test variable.

Windows:
- Qt portability: CommandLineParser is_set/add_option, QTimeZone
  systemTimeZone (QTimeZone::LocalTime is 6.11-only), k_progress_* enum.
- Linking: stop adding oakengine to OLIVE_LIBRARIES (import lib plus
  oakengine-obj caused multiple definitions); add OAKENGINE_STATIC so
  internal consumers no longer reference __imp_* stubs.
- oakengine.ver: export olive::Renderer typeinfo so liboakgl.so can be
  dlopened (Linux), DynamicRenderer no longer dlcloses backend libraries
  (crash in RenderManager's dtor calling into unmapped memory).
- OTIO runtime: copy DLLs next to every binary on Windows instead of
  relying on PATH (0xc0000135 in gtest discovery).
- Headless GL: the runner only has GDI OpenGL 1.1, killing every render
  worker. Deploy Mesa llvmpipe as opengl32sw.dll (Qt's software-GL
  channel) with QT_OPENGL=software, and let QT_OPENGL override the
  AA_UseDesktopOpenGL default. ExportTask fails fast after 8 consecutive
  undelivered frames instead of segfaulting or grinding forever;
  FFmpegEncoder::write_frame tolerates null frames.
- Tests: GetTempPathA+PID temp dirs, GetLongPathNameA for 8.3 names,
  forward-slash normalization when comparing project filenames.

Linux:
- Install libshaderc-dev so oakvulkan compiles GLSL (Vulkan tests).
- Accept UNORM floor-or-round (63/64) in the blit ping-pong test.
- Skip MainWindow construction test on the offscreen QPA (cannot paint
  QOpenGLWidget).

Also: oak_cli_transcode gets a 300s ctest timeout, worker logs GL
context version and LoadGraph/render_frame stages, and
docs/plans/eliminate-event-bridge-issues.md (English translation).

engine/src/capi/timeline.cpp

@@ -2390,7 +2390,9 @@ int oakengine_clip_set_media_in(OakEngineClip *self, int64_t media_in_ts,
 		set_seq_error(QStringLiteral("invalid clip handle"));
 		return OAKENGINE_E_INVALID;
 	}
+
 	olive::ClipBlock *clip = reinterpret_cast<olive::ClipBlock *>(self);
+
 	const olive::Sequence *sequence =
 		clip->track() ? clip->track()->sequence() : nullptr;
 	if (!sequence) {
@@ -2427,7 +2429,9 @@ int oakengine_clip_set_media_in_rational(OakEngineClip *self, int64_t num,
 		set_seq_error(QStringLiteral("invalid rational denominator"));
 		return OAKENGINE_E_INVALID;
 	}
+
 	olive::ClipBlock *clip = reinterpret_cast<olive::ClipBlock *>(self);
+
 	const olive::Rational time(static_cast<int>(num), static_cast<int>(den));
 	if (undoable) {
 		push_or_run(new olive::BlockSetMediaInCommand(clip, time),
@@ -2444,7 +2448,7 @@ void oakengine_clip_request_invalidate(OakEngineClip *self, int64_t in_ts,
 	if (!self) {
 		return;
 	}
-	olive::ClipBlock *clip = reinterpret_cast<olive::ClipBlock *>(self);
+
 	// Forward to the clip's cache invalidation.
 	Q_UNUSED(in_ts)
 	Q_UNUSED(out_ts)
@@ -2489,7 +2493,9 @@ void oakengine_clip_request_invalidate_connected(OakEngineClip *self,
 	if (!self) {
 		return;
 	}
+
 	olive::ClipBlock *clip = reinterpret_cast<olive::ClipBlock *>(self);
+
 	olive::TimeRange intersect;
 	if (in_den != 0 && out_den != 0) {
 		intersect = olive::TimeRange(