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/plugin.cpp

@@ -61,13 +61,13 @@ int oakengine_plugin_set_progress_reporter_factory(
     oakengine_plugin_reporter_create_fn create,
     oakengine_plugin_reporter_destroy_fn destroy,
     oakengine_plugin_reporter_is_cancelled_fn is_cancelled,
-    oakengine_plugin_reporter_set_progress_fn set_progress,
+    oakengine_plugin_reporter_set_progress_fn set_progress_fn,
     void *userdata)
 {
     g_reporter_create = create;
     g_reporter_destroy = destroy;
     g_reporter_is_cancelled = is_cancelled;
-    g_reporter_set_progress = set_progress;
+    g_reporter_set_progress = set_progress_fn;
     g_reporter_userdata = userdata;
 
     // Register factory with the engine.
@@ -90,12 +90,12 @@ int oakengine_plugin_set_progress_reporter_factory(
                 CAdapter(void *reporter,
                          oakengine_plugin_reporter_destroy_fn destroy,
                          oakengine_plugin_reporter_is_cancelled_fn is_cancelled,
-                         oakengine_plugin_reporter_set_progress_fn set_progress,
+                         oakengine_plugin_reporter_set_progress_fn set_progress_fn,
                          void *userdata)
                     : PluginProgressReporter()
                     , reporter_(reporter)
                     , destroy_(destroy)
-                    , set_progress_(set_progress)
+                    , set_progress_(set_progress_fn)
                     , userdata_(userdata) {}
                 ~CAdapter() override
                 {