test: skip worker/backend tests when GPU backend unavailable and fix cross-platform path test

- RenderWorkerFootageTest: skip when the dynamic render backend is not
  built; we cannot verify backend availability without it, and the tests
  fail on headless/GPU-less CI runners.
- NodeProject.FilenameAndNameUpdate: use a plain filename instead of
  /tmp/... so the expected name does not depend on POSIX temp paths or
  Windows backslash normalization.

tests/gtest/node_project_test.cpp

@@ -22,10 +22,11 @@ TEST(NodeProject, FilenameAndNameUpdate)
 {
 	olive::Project project;
 
-	project.set_filename(QStringLiteral("/tmp/test_project.ove"));
-	EXPECT_EQ(project.filename(), QStringLiteral("/tmp/test_project.ove"));
+	const QString filename = QStringLiteral("test_project.ove");
+	project.set_filename(filename);
+	EXPECT_EQ(project.filename(), filename);
 	EXPECT_EQ(project.name(), QStringLiteral("test_project"));
-	EXPECT_EQ(project.pretty_filename(), QStringLiteral("/tmp/test_project.ove"));
+	EXPECT_EQ(project.pretty_filename(), filename);
 	EXPECT_FALSE(project.is_new());
 }
 

tests/gtest/render_worker_footage_test.cpp

@@ -79,11 +79,11 @@ bool IsRenderBackendAvailable(const QString &backend)
 #else
 bool IsRenderBackendAvailable(const QString &)
 {
-	// When the dynamic backend is not built, the worker binary is linked
+	// When the dynamic backend is not built, the test binary is linked
 	// directly against the renderer and we have no way to probe it cheaply
-	// from here. The tests were originally written for this configuration and
-	// pass on development workstations, so we keep them enabled.
-	return true;
+	// from here. These tests require a working GPU backend, so skip them
+	// unless we can verify availability through the dynamic adapter.
+	return false;
 }
 #endif