fix(ci): give the Windows tests vcpkg's DLLs; skip root-only perm checks

- Windows: the first test executable died with STATUS_DLL_NOT_FOUND
  (0xc0000135) because vcpkg's x64-windows DLLs (ffmpeg and its codecs)
  were not on PATH; add vcpkg_installed/x64-windows/bin in the configure
  step.
- openKylin: failure_paths_report_cleanly asserts that a read-only library
  write fails, but the container runs as root, which bypasses the file
  permission bits (CAP_DAC_OVERRIDE) and the write succeeds; skip that
  sub-check when euid is 0 (read from /proc/self/status on Linux) and note
  it in the log.

.github/workflows/ci.yml

@@ -340,6 +340,10 @@ jobs:
           "FFMPEG_DIR=$prefix" >> $env:GITHUB_ENV
           "PKG_CONFIG_PATH=$prefix\lib\pkgconfig" >> $env:GITHUB_ENV
           "$prefix\tools\pkgconf" >> $env:GITHUB_PATH
+          # The test binaries link vcpkg's dynamic DLLs (ffmpeg and its
+          # codecs): without this the runner reports STATUS_DLL_NOT_FOUND
+          # when the first test executable starts.
+          "$prefix\bin" >> $env:GITHUB_PATH
           # Bundled OCIO: ocio-sys' vendored sources build with the MSVC
           # toolchain (what they need — the MSYS2 package was the
           # workaround, not the preference), so no OCIO_INSTALL_DIR and

crates/oak-storage/tests/database_test.rs

@@ -1090,6 +1090,28 @@ fn invalid_uri_matrix() {
 	);
 }
 
+/// Linux CI containers run as root, which bypasses the file permission bits
+/// (`CAP_DAC_OVERRIDE`), so the read-only failure paths cannot be exercised
+/// there.
+#[cfg(target_os = "linux")]
+fn running_as_root() -> bool {
+	std::fs::read_to_string("/proc/self/status")
+		.ok()
+		.and_then(|status| {
+			status
+				.lines()
+				.find(|line| line.starts_with("Uid:"))
+				.and_then(|line| line.split_whitespace().nth(1).map(str::to_string))
+		})
+		.map(|uid| uid == "0")
+		.unwrap_or(false)
+}
+
+#[cfg(not(target_os = "linux"))]
+fn running_as_root() -> bool {
+	false
+}
+
 /// Write failures surface as errors, not panics or silent corruption:
 /// (a) read-only database files, (b) an out-of-range undo target, and
 /// (c) concurrent writers on one file.
@@ -1120,8 +1142,15 @@ fn failure_paths_report_cleanly() {
 		std::fs::set_permissions(f, p).unwrap();
 	}
 	let fresh = DatabaseBackend::new();
-	let err = save_project(&fresh, &project, &uri).err().unwrap();
-	assert_eq!(err.code(), OAKSTORAGE_E_IO, "read-only library write must fail");
+	let result = save_project(&fresh, &project, &uri);
+	if running_as_root() {
+		// The openKylin CI container runs as root: the read-only bits do not
+		// stop the write, so the failure cannot be asserted here.
+		println!("SKIP: read-only library write check needs an unprivileged user");
+	} else {
+		let err = result.err().expect("read-only library write must fail");
+		assert_eq!(err.code(), OAKSTORAGE_E_IO, "read-only library write must fail");
+	}
 	for (f, p) in targets.iter().zip(saved) {
 		std::fs::set_permissions(f, p).unwrap();
 	}