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/render/opengl/openglrenderer.cpp

@@ -558,6 +558,8 @@ void OpenGLRenderer::blit(QVariant s, AcceleratedJob &a_job,
 				// over/underflows if the number is large enough, but the likelihood of that is quite low.
 				functions_->glUniform1i(variable_location, value.to_int());
 				break;
+		default:
+			break;
 			case NodeValue::k_float:
 				// kFloat technically specifies a double but as above, OpenGL doesn't support those.
 				functions_->glUniform1f(variable_location, value.to_double());
@@ -828,7 +830,7 @@ void OpenGLRenderer::blit(QVariant s, AcceleratedJob &a_job,
 		vert_vbo.destroy();
 		vao.release();
 		vao.destroy();
-	} catch (std::bad_cast e) {
+	} catch (const std::bad_cast &e) {
 	}
 }
 
@@ -975,7 +977,6 @@ GLuint OpenGLRenderer::compile_shader(GLenum type, const QString &code)
 {
 	const bool is_gles = context_ && context_->isOpenGLES();
 	const int major = context_ ? context_->format().majorVersion() : 0;
-	const int minor = context_ ? context_->format().minorVersion() : 0;
 	const bool is_gles2 = is_gles && (major < 3);
 	const QString gles_preamble =
 		is_gles2 ? QStringLiteral("#version 100\n\n"