test(config): skip permission test when running as root

The Gitea CI runner executes as root, which bypasses filesystem
permission checks. The TestLoad_ReadError test creates a mode-0000 file
and expects a read error, but root can always read files regardless of
mode. Skip the test under root instead of removing it so it still runs
in restricted environments.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/config/config_test.go

@@ -103,6 +103,9 @@ func TestLoad_StopsAtGitRoot(t *testing.T) {
 // TestLoad_ReadError covers the !os.IsNotExist(err) branch (config.go:59-61)
 // when the file exists but is not readable.
 func TestLoad_ReadError(t *testing.T) {
+	if os.Getuid() == 0 {
+		t.Skip("skipping: root bypasses file permission checks")
+	}
 	tmp := t.TempDir()
 	cfgPath := filepath.Join(tmp, Filename)
 	if err := os.WriteFile(cfgPath, []byte("ignore: []"), 0o000); err != nil {