import
Applies export to this model's controls, updating each control whose key is found in the respective map.
Processing order: numeric → string → JSON. Within each family every entry is attempted independently:
A key present in export but absent from this model is added to ControlImportResult.missingKeys and logged at WARN.
A string or JSON value rejected by validation is caught, added to ControlImportResult.failures, and logged at WARN.
Numeric values are clamped to declared bounds by the setter and never produce a validation failure.
Return
a ControlImportResult summarising successes, validation failures, and missing keys across all three families