feat: add dependency status to --version and document AppArmor userns fix

Show installed dependencies, security features, and transparent proxy
availability when running --version. Detect AppArmor
unprivileged_userns restriction on Ubuntu 24.04+ and suggest the fix.
Document the RTM_NEWADDR issue in experience.md.

cmd/greywall/main.go

@@ -125,6 +125,7 @@ func runCommand(cmd *cobra.Command, args []string) error {
 		fmt.Printf("  Version: %s\n", version)
 		fmt.Printf("  Built:   %s\n", buildTime)
 		fmt.Printf("  Commit:  %s\n", gitCommit)
+		sandbox.PrintDependencyStatus()
 		return nil
 	}