fix: skip keychain test on non-macOS platforms

The wrapKeychainError test was failing on Linux CI because
IsKeychainLockedError always returns false on non-Darwin platforms.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: salmonumbrella

internal/secrets/store_test.go

@@ -107,6 +107,10 @@ var (
 )
 
 func TestWrapKeychainError(t *testing.T) {
+	if !IsKeychainLockedError("User Interaction is not allowed. (-25308)") {
+		t.Skip("wrapKeychainError only wraps errors on macOS")
+	}
+
 	tests := []struct {
 		name        string
 		err         error