chore(env): update Govulncheck Go version to 1.25.5

Author: mrz1836

.github/.env.base

@@ -39,7 +39,7 @@ GO_SECONDARY_VERSION=1.24.x
 # Govulncheck-specific Go version for vulnerability scanning
 # Uses newer Go version for accurate standard library vulnerability detection
 # Override this in .env.custom if needed for compatibility
-GOVULNCHECK_GO_VERSION=1.25.x
+GOVULNCHECK_GO_VERSION=1.25.5
 
 # ================================================================================================
 # 📦 GO MODULE CONFIGURATION