Add 3 error-tolerance toggles to IIS deploy (P2-1)
Bundles IgnoreVariableReplacementErrors + ShouldFailDeploymentOnSubstitutionFails + EnableDiagnosticsConfigTransformationLogging. All Octopus-parity. +4 real-host tests. BEHAVIOR CHANGE: ConfigurationVariables now THROWS on malformed XML by default (was silent skip); operators flip the flag to restore prior leniency.